style: run pre-commit on linewidth

Henry Schreiner · Henry Schreiner
1 parent c1465e61
Showing 22 changed files with 2128 additions and 785 deletions
.appveyor.yml
.ci/azure-build.yml
.ci/azure-cmake.yml
.clang-tidy
.github/CONTRIBUTING.md
CHANGELOG.md
README.md
azure-pipelines.yml
book/README.md
book/chapters/advanced-topics.md
book/chapters/an-advanced-example.md
book/chapters/basics.md
book/chapters/config.md
book/chapters/flags.md
book/chapters/formatting.md
book/chapters/installation.md
book/chapters/internals.md
book/chapters/options.md
book/chapters/subcommands.md
book/chapters/toolkits.md
@@ -19,7 +19,9 @@ install:
 build_script:
   - mkdir build
   - cd build
-  - ps: cmake .. -DCLI11_WARNINGS_AS_ERRORS=ON -DCLI11_SINGLE_FILE_TESTS=ON -DCMAKE_BUILD_TYPE=Debug -DCMAKE_GENERATOR="Visual Studio 14 2015"
+  - ps:
+      cmake .. -DCLI11_WARNINGS_AS_ERRORS=ON -DCLI11_SINGLE_FILE_TESTS=ON
+      -DCMAKE_BUILD_TYPE=Debug -DCMAKE_GENERATOR="Visual Studio 14 2015"
   - ps: cmake --build .
   - cd ..
   - conan create . CLIUtils/CLI11
 steps:
   - task: CMake@1
     inputs:
-      cmakeArgs: .. -DCLI11_WARNINGS_AS_ERRORS=ON -DCLI11_SINGLE_FILE=$(cli11.single) -DCMAKE_CXX_STANDARD=$(cli11.std) -DCLI11_SINGLE_FILE_TESTS=$(cli11.single) -DCMAKE_BUILD_TYPE=$(cli11.build_type) $(cli11.options)
+      cmakeArgs:
+        .. -DCLI11_WARNINGS_AS_ERRORS=ON -DCLI11_SINGLE_FILE=$(cli11.single)
+        -DCMAKE_CXX_STANDARD=$(cli11.std)
+        -DCLI11_SINGLE_FILE_TESTS=$(cli11.single)
+        -DCMAKE_BUILD_TYPE=$(cli11.build_type) $(cli11.options)
     displayName: "Configure"
  
   - script: cmake --build .
@@ -11,5 +11,7 @@ steps:
       destinationFolder: "cmake_program"
       displayName: Extract CMake
  
-  - bash: echo "##vso[task.prependpath]$(Build.SourcesDirectory)/cmake_program/cmake-3.14.3-Linux-x86_64/bin"
+  - bash:
+      echo
+      "##vso[task.prependpath]$(Build.SourcesDirectory)/cmake_program/cmake-3.14.3-Linux-x86_64/bin"
     displayName: Add CMake to PATH
@@ -4,15 +4,9 @@
 FormatStyle: file
  
 Checks: >
-  -*,
-  google-*,
-  -google-runtime-references,
-  llvm-include-order,
-  llvm-namespace-comment,
-  misc-throw-by-value-catch-by-reference,
-  modernize*,
-  -modernize-use-trailing-return-type,
-  readability-container-size-empty,
+  -*, google-*, -google-runtime-references, llvm-include-order,
+  llvm-namespace-comment, misc-throw-by-value-catch-by-reference, modernize*,
+  -modernize-use-trailing-return-type, readability-container-size-empty,
  
 WarningsAsErrors: "*"
  
 # Contributing
  
-Thanks for considering to write a Pull Request (PR) for CLI11! Here are a few guidelines to get you started:
+Thanks for considering to write a Pull Request (PR) for CLI11! Here are a few
+guidelines to get you started:
  
-Make sure you are comfortable with the license; all contributions are licensed under the original license.
+Make sure you are comfortable with the license; all contributions are licensed
+under the original license.
  
 ## Adding functionality
  
@@ -13,25 +15,36 @@ Make sure any new functions you add are are:
 - Explained in your PR (or previously explained in an Issue mentioned in the PR)
 - Completely covered by tests
  
-In general, make sure the addition is well thought out and does not increase the complexity of CLI11 needlessly.
+In general, make sure the addition is well thought out and does not increase the
+complexity of CLI11 needlessly.
  
 ## Things you should know
  
-- Once you make the PR, tests will run to make sure your code works on all supported platforms
+- Once you make the PR, tests will run to make sure your code works on all
+  supported platforms
 - The test coverage is also measured, and that should remain 100%
-- Formatting should be done with pre-commit, otherwise the format check will not pass. However, it is trivial to apply this to your PR, so don't worry about this check. If you do want to run it, see below.
-- Everything must pass clang-tidy as well, run with `-DCLI11_CLANG_TIDY=ON` (if you set `-DCLI11_CLANG_TIDY_OPTIONS="-fix"`, make sure you use a single threaded build process, or just build one example target).
-- Your changes must also conform to most of the [Google C++ Style Guide](https://google.github.io/styleguide/cppguide.html) rules checked by [cpplint](https://github.com/cpplint/cpplint). For unused cpplint filters and justifications, see [CPPLINT.cfg](/CPPLINT.cfg).
+- Formatting should be done with pre-commit, otherwise the format check will not
+  pass. However, it is trivial to apply this to your PR, so don't worry about
+  this check. If you do want to run it, see below.
+- Everything must pass clang-tidy as well, run with `-DCLI11_CLANG_TIDY=ON` (if
+  you set `-DCLI11_CLANG_TIDY_OPTIONS="-fix"`, make sure you use a single
+  threaded build process, or just build one example target).
+- Your changes must also conform to most of the
+  [Google C++ Style Guide](https://google.github.io/styleguide/cppguide.html)
+  rules checked by [cpplint](https://github.com/cpplint/cpplint). For unused
+  cpplint filters and justifications, see [CPPLINT.cfg](/CPPLINT.cfg).
  
 ## Pre-commit
  
-Format is handled by pre-commit. You should install it (or use [pipx](https://pypa.github.io/pipx/)):
+Format is handled by pre-commit. You should install it (or use
+[pipx](https://pypa.github.io/pipx/)):
  
 ```bash
 python3 -m pip install pre-commit
 ```
  
-Then, you can run it on the items you've added to your staging area, or all files:
+Then, you can run it on the items you've added to your staging area, or all
+files:
  
 ```bash
 pre-commit run
@@ -39,7 +52,8 @@ pre-commit run
 pre-commit run --all-files
 ```
  
-And, if you want to always use it, you can install it as a git hook (hence the name, pre-commit):
+And, if you want to always use it, you can install it as a git hook (hence the
+name, pre-commit):
  
 ```bash
 pre-commit install
@@ -47,7 +61,8 @@ pre-commit install
  
 ## For developers releasing to Conan.io
  
-This is now done by the CI system on tagged releases. Previously, the steps to make a Conan.io release were:
+This is now done by the CI system on tagged releases. Previously, the steps to
+make a Conan.io release were:
  
 ```bash
 conan remove '*' # optional, I like to be clean
@@ -59,7 +74,10 @@ Here I&#39;ve assumed that the remote is `cli11`.
  
 ## For maintainers: remember to add contributions
  
-In a commit to a PR, just add "`@all-contributors please add <username> for <contributions>`" or similar (see <https://allcontributors.org>). Use `code` for code, `bug` if an issue was submitted, `platform` for packaging stuff, and `doc` for documentation updates.
+In a commit to a PR, just add
+"`@all-contributors please add <username> for <contributions>`" or similar (see
+<https://allcontributors.org>). Use `code` for code, `bug` if an issue was
+submitted, `platform` for packaging stuff, and `doc` for documentation updates.
  
 To run locally, do:
  
@@ -70,7 +88,8 @@ yarn all-contributors add username code,bug
  
 ## For maintainers: Making a release
  
-Remember to replace the emoji in the readme, being careful not to replace the ones in all-contributors if any overlap.
+Remember to replace the emoji in the readme, being careful not to replace the
+ones in all-contributors if any overlap.
  
 Steps:
  
@@ -2,28 +2,55 @@
  
 ## Version 2.2: Option and Configuration Flexibility
  
-New features include support for output of an empty vector, a summing option policy that can be applied more broadly, and an option to validate optional arguments to discriminate from positional arguments. A new validator to check for files on a default path is included to allow one or more default paths for configuration files or other file arguments. A number of bug fixes and code cleanup for various build configurations. Clean up of some error outputs and extension of existing capability to new types or situations.
-
-There is a possible minor breaking change in behavior of certain types which wrapped an integer, such as `std::atomic<int>` or `std::optional<int>` when used in a flag. The default behavior is now as a single argument value vs. summing all the arguments. The default summing behavior is now restricted to pure integral types, int64_t, int, uint32_t, etc. Use the new `sum` multi option policy to revert to the older behavior. The summing behavior on wrapper types was not originally intended.
-
-- Add `MultiOptionPolicy::Sum` and refactor the `add_flag` to fix a bug when using `std::optional<bool>` as type. [#709][]
-- Add support for an empty vector result in TOML and as a default string. [#660][]
-- Add `.validate_optional_arguments()` to support discriminating positional arguments from vector option arguments. [#668][]
-- Add `CLI::FileOnDefaultPath` to check for files on a specified default path. [#698][]
-- Change default value display in help messages from `=XXXX` to `[XXXXX]` to make it clearer. [#666][]
-- Modify the Range Validator to support additional types and clean up the error output. [#690][]
-- Bugfix: The trigger on parse modifier did not work on positional argument.s [#713][]
-- Bugfix: The single header file generation was missing custom namespace generation. [#707][]
+New features include support for output of an empty vector, a summing option
+policy that can be applied more broadly, and an option to validate optional
+arguments to discriminate from positional arguments. A new validator to check
+for files on a default path is included to allow one or more default paths for
+configuration files or other file arguments. A number of bug fixes and code
+cleanup for various build configurations. Clean up of some error outputs and
+extension of existing capability to new types or situations.
+
+There is a possible minor breaking change in behavior of certain types which
+wrapped an integer, such as `std::atomic<int>` or `std::optional<int>` when used
+in a flag. The default behavior is now as a single argument value vs. summing
+all the arguments. The default summing behavior is now restricted to pure
+integral types, int64_t, int, uint32_t, etc. Use the new `sum` multi option
+policy to revert to the older behavior. The summing behavior on wrapper types
+was not originally intended.
+
+- Add `MultiOptionPolicy::Sum` and refactor the `add_flag` to fix a bug when
+  using `std::optional<bool>` as type. [#709][]
+- Add support for an empty vector result in TOML and as a default string.
+  [#660][]
+- Add `.validate_optional_arguments()` to support discriminating positional
+  arguments from vector option arguments. [#668][]
+- Add `CLI::FileOnDefaultPath` to check for files on a specified default path.
+  [#698][]
+- Change default value display in help messages from `=XXXX` to `[XXXXX]` to
+  make it clearer. [#666][]
+- Modify the Range Validator to support additional types and clean up the error
+  output. [#690][]
+- Bugfix: The trigger on parse modifier did not work on positional argument.s
+  [#713][]
+- Bugfix: The single header file generation was missing custom namespace
+  generation. [#707][]
 - Bugfix: Clean up File Error handling in the argument processing. [#678][]
-- Bugfix: Fix a stack overflow error if nameless commands had fallthrough. [#665][]
-- Bugfix: A subcommand callback could be executed multiple times if it was a member of an option group. [#666][]
-- Bugfix: Fix an issue with vectors of multi argument types where partial argument sets did not result in an error. [#661][]
-- Bugfix: Fix an issue with type the template matching on C++20 and add some CI builds for C++20. [#663][]
+- Bugfix: Fix a stack overflow error if nameless commands had fallthrough.
+  [#665][]
+- Bugfix: A subcommand callback could be executed multiple times if it was a
+  member of an option group. [#666][]
+- Bugfix: Fix an issue with vectors of multi argument types where partial
+  argument sets did not result in an error. [#661][]
+- Bugfix: Fix an issue with type the template matching on C++20 and add some CI
+  builds for C++20. [#663][]
 - Bugfix: Fix typo in C++20 detection on MSVC. [#706][]
-- Bugfix: An issue where the detection of RTTI being disabled on certain MSVC platforms did not disable the use of dynamic cast calls. [#666][]
+- Bugfix: An issue where the detection of RTTI being disabled on certain MSVC
+  platforms did not disable the use of dynamic cast calls. [#666][]
 - Bugfix: Resolve strict-overflow warning on some GCC compilers. [#666][]
-- Backend: Add additional tests concerning the use of aliases for option groups in config files. [#666][]
-- Build: Add support for testing in meson and cleanup symbolic link generation. [#701][], [#697][]
+- Backend: Add additional tests concerning the use of aliases for option groups
+  in config files. [#666][]
+- Build: Add support for testing in meson and cleanup symbolic link generation.
+  [#701][], [#697][]
 - Build: Support building in WebAssembly. [#679][]
  
 [#660]: https://github.com/CLIUtils/CLI11/pull/660
@@ -49,15 +76,21 @@ The name restrictions for options and subcommands are now much looser, allowing
 a wider variety of characters than before, even spaces can be used (use quotes
 to include a space in most shells). The default configuration parser was
 improved, allowing your configuration to sit in a larger file. And option
-callbacks have a few new settings, allowing them to be run even if the option
-is not passed, or every time the option is parsed.
-
-- Option/subcommand name restrictions have been relaxed. Most characters are now allowed. [#627][]
-- The config parser can accept streams, specify a specific section, and inline comment characters are supported [#630][]
-- `force_callback` & `trigger_on_parse` added, allowing a callback to always run on parse even if not present or every time the option is parsed [#631][]
-- Bugfix(cmake): Only add `CONFIGURE_DEPENDS` if CLI11 is the main project [#633][]
-- Bugfix(cmake): Ensure the cmake/pkg-config files install to a arch independent path [#635][]
-- Bugfix: The single header file generation was missing the include guard. [#620][]
+callbacks have a few new settings, allowing them to be run even if the option is
+not passed, or every time the option is parsed.
+
+- Option/subcommand name restrictions have been relaxed. Most characters are now
+  allowed. [#627][]
+- The config parser can accept streams, specify a specific section, and inline
+  comment characters are supported [#630][]
+- `force_callback` & `trigger_on_parse` added, allowing a callback to always run
+  on parse even if not present or every time the option is parsed [#631][]
+- Bugfix(cmake): Only add `CONFIGURE_DEPENDS` if CLI11 is the main project
+  [#633][]
+- Bugfix(cmake): Ensure the cmake/pkg-config files install to a arch independent
+  path [#635][]
+- Bugfix: The single header file generation was missing the include guard.
+  [#620][]
  
 [#620]: https://github.com/CLIUtils/CLI11/pull/620
 [#627]: https://github.com/CLIUtils/CLI11/pull/627
@@ -70,7 +103,8 @@ is not passed, or every time the option is parsed.
  
 - A collision with `min`/`max` macros on Windows has been fixed. [#642][]
 - Tests pass with Boost again [#646][]
-- Running the pre-commit hooks in development no longer requires docker for clang-format [#647][]
+- Running the pre-commit hooks in development no longer requires docker for
+  clang-format [#647][]
  
 [#642]: https://github.com/CLIUtils/CLI11/pull/642
 [#646]: https://github.com/CLIUtils/CLI11/pull/646
@@ -92,11 +126,11 @@ is not passed, or every time the option is parsed.
  
 This version focuses on cleaning up deprecated functionality, and some minor
 default changes. The config processing is TOML compliant now. Atomics and
-complex numbers are directly supported, along with other container
-improvements. A new version flag option has finally been added. Subcommands are
-significantly improved with new features and bugfixes for corner cases. This
-release contains a lot of backend cleanup, including a complete overhaul of the
-testing system and single file generation system.
+complex numbers are directly supported, along with other container improvements.
+A new version flag option has finally been added. Subcommands are significantly
+improved with new features and bugfixes for corner cases. This release contains
+a lot of backend cleanup, including a complete overhaul of the testing system
+and single file generation system.
  
 - Built-in config format is TOML compliant now [#435][]
   - Support multiline TOML [#528][]
@@ -109,13 +143,15 @@ testing system and single file generation system.
 - Support `->silent()` on subcommands. [#529][]
 - Add alias section to help for subcommands [#545][]
 - Allow quotes to specify a program name [#605][]
-- Backend: redesigned MakeSingleFiles to have a higher level of manual control, to support future features. [#546][]
+- Backend: redesigned MakeSingleFiles to have a higher level of manual control,
+  to support future features. [#546][]
 - Backend: moved testing from GTest to Catch2 [#574][]
 - Bugfix: avoid duplicated and missed calls to the final callback [#584][]
 - Bugfix: support embedded newlines in more places [#592][]
 - Bugfix: avoid listing helpall as a required flag [#530][]
 - Bugfix: avoid a clash with WINDOWS define [#563][]
-- Bugfix: the help flag didn't get processed when a config file was required [#606][]
+- Bugfix: the help flag didn't get processed when a config file was required
+  [#606][]
 - Bugfix: fix description of non-configurable subcommands in config [#604][]
 - Build: support pkg-config [#523][]
  
@@ -123,9 +159,10 @@ testing system and single file generation system.
 >
 > - Removed deprecated set commands, use validators instead. [#565][]
 > - The final "defaulted" bool has been removed, use `->capture_default_str()`
->   instead. Use `app.option_defaults()->always_capture_default()` to set this for
->   all future options. [#597][]
-> - Use `add_option` on a complex number instead of `add_complex`, which has been removed.
+>   instead. Use `app.option_defaults()->always_capture_default()` to set this
+>   for all future options. [#597][]
+> - Use `add_option` on a complex number instead of `add_complex`, which has
+>   been removed.
  
 [#423]: https://github.com/CLIUtils/CLI11/pull/423
 [#435]: https://github.com/CLIUtils/CLI11/pull/435
@@ -153,23 +190,30 @@ testing system and single file generation system.
  
 ## Version 1.9: Config files and cleanup
  
-Config file handling was revamped to fix common issues, and now supports reading [TOML](https://github.com/toml-lang/toml).
+Config file handling was revamped to fix common issues, and now supports reading
+[TOML](https://github.com/toml-lang/toml).
  
 Adding options is significantly more powerful with support for things like
 `std::tuple` and `std::array`, including with transforms. Several new
-configuration options were added to facilitate a wider variety of apps. GCC
-4.7 is no longer supported.
+configuration options were added to facilitate a wider variety of apps. GCC 4.7
+is no longer supported.
  
-- Config files refactored, supports TOML (may become default output in 2.0) [#362][]
-- Added two template parameter form of `add_option`, allowing `std::optional` to be supported without a special import [#285][]
+- Config files refactored, supports TOML (may become default output in 2.0)
+  [#362][]
+- Added two template parameter form of `add_option`, allowing `std::optional` to
+  be supported without a special import [#285][]
 - `string_view` now supported in reasonable places [#300][], [#285][]
-- `immediate_callback`, `final_callback`, and `parse_complete_callback` added to support controlling the App callback order [#292][], [#313][]
-- Multiple positional arguments maintain order if `positionals_at_end` is set. [#306][]
-- Pair/tuple/array now supported, and validators indexed to specific components in the objects [#307][], [#310][]
+- `immediate_callback`, `final_callback`, and `parse_complete_callback` added to
+  support controlling the App callback order [#292][], [#313][]
+- Multiple positional arguments maintain order if `positionals_at_end` is set.
+  [#306][]
+- Pair/tuple/array now supported, and validators indexed to specific components
+  in the objects [#307][], [#310][]
 - Footer callbacks supported [#309][]
 - Subcommands now support needs (including nameless subcommands) [#317][]
 - More flexible type size, more useful `add_complex` [#325][], [#370][]
-- Added new validators `CLI::NonNegativeNumber` and `CLI::PositiveNumber` [#342][]
+- Added new validators `CLI::NonNegativeNumber` and `CLI::PositiveNumber`
+  [#342][]
 - Transform now supports arrays [#349][]
 - Option groups can be hidden [#356][]
 - Add `CLI::deprecate_option` and `CLI::retire_option` functions [#358][]
@@ -178,23 +222,29 @@ configuration options were added to facilitate a wider variety of apps. GCC
 - Backend: File checking updates [#341][]
 - Backend: Using pre-commit to format, checked in GitHub Actions [#336][]
 - Backend: Clang-tidy checked again, CMake option now `CL11_CLANG_TIDY` [#390][]
-- Backend: Warning cleanup, more checks from klocwork [#350][], Effective C++ [#354][], clang-tidy [#360][], CUDA NVCC [#365][], cross compile [#373][], sign conversion [#382][], and cpplint [#400][]
-- Docs: CLI11 Tutorial now hosted in the same repository [#304][], [#318][], [#374][]
+- Backend: Warning cleanup, more checks from klocwork [#350][], Effective C++
+  [#354][], clang-tidy [#360][], CUDA NVCC [#365][], cross compile [#373][],
+  sign conversion [#382][], and cpplint [#400][]
+- Docs: CLI11 Tutorial now hosted in the same repository [#304][], [#318][],
+  [#374][]
 - Bugfix: Fixed undefined behavior in `checked_multiply` [#290][]
 - Bugfix: `->check()` was adding the name to the wrong validator [#320][]
 - Bugfix: Resetting config option works properly [#301][]
 - Bugfix: Hidden flags were showing up in error printout [#333][]
 - Bugfix: Enum conversion no longer broken if stream operator added [#348][]
 - Build: The meson build system supported [#299][]
-- Build: GCC 4.7 is no longer supported, due mostly to GoogleTest. GCC 4.8+ is now required. [#160][]
+- Build: GCC 4.7 is no longer supported, due mostly to GoogleTest. GCC 4.8+ is
+  now required. [#160][]
 - Build: Restructured significant portions of CMake build system [#394][]
  
 > ### Converting from CLI11 1.8
 >
 > - Some deprecated methods dropped
->   - `add_set*` should be replaced with `->check`/`->transform` and `CLI::IsMember` since 1.8
+>   - `add_set*` should be replaced with `->check`/`->transform` and
+>     `CLI::IsMember` since 1.8
 >   - `get_defaultval` was replaced by `get_default_str` in 1.8
-> - The true/false 4th argument to `add_option` is expected to be removed in 2.0, use `->capture_default_str()` since 1.8
+> - The true/false 4th argument to `add_option` is expected to be removed in
+>   2.0, use `->capture_default_str()` since 1.8
  
 [#160]: https://github.com/CLIUtils/CLI11/pull/160
 [#285]: https://github.com/CLIUtils/CLI11/pull/285
@@ -258,41 +308,73 @@ This is a patch version that backports fixes from the development of 2.0.
  
 ## Version 1.8: Transformers, default strings, and flags
  
-Set handling has been completely replaced by a new backend that works as a Validator or Transformer. This provides a single interface instead of the 16 different functions in App. It also allows ordered collections to be used, custom functions for filtering, and better help and error messages. You can also use a collection of pairs (like `std::map`) to transform the match into an output. Also new are inverted flags, which can cancel or reduce the count of flags, and can also support general flag types. A new `add_option_fn` lets you more easily program CLI11 options with the types you choose. Vector options now support a custom separator. Apps can now be composed with unnamed subcommand support. The final bool "defaults" flag when creating options has been replaced by `->capture_default_str()` (ending an old limitation in construction made this possible); the old method is still available but may be removed in future versions.
-
-- Replaced default help capture: `.add_option("name", value, "", True)` becomes `.add_option("name", value)->capture_default_str()` [#242][]
+Set handling has been completely replaced by a new backend that works as a
+Validator or Transformer. This provides a single interface instead of the 16
+different functions in App. It also allows ordered collections to be used,
+custom functions for filtering, and better help and error messages. You can also
+use a collection of pairs (like `std::map`) to transform the match into an
+output. Also new are inverted flags, which can cancel or reduce the count of
+flags, and can also support general flag types. A new `add_option_fn` lets you
+more easily program CLI11 options with the types you choose. Vector options now
+support a custom separator. Apps can now be composed with unnamed subcommand
+support. The final bool "defaults" flag when creating options has been replaced
+by `->capture_default_str()` (ending an old limitation in construction made this
+possible); the old method is still available but may be removed in future
+versions.
+
+- Replaced default help capture: `.add_option("name", value, "", True)` becomes
+  `.add_option("name", value)->capture_default_str()` [#242][]
 - Added `.always_capture_default()` [#242][]
 - New `CLI::IsMember` validator replaces set validation [#222][]
-- `IsMember` also supports container of pairs, transform allows modification of result [#228][]
-- Added new Transformers, `CLI::AsNumberWithUnit` and `CLI::AsSizeValue` [#253][]
-- Much more powerful flags with different values [#211][], general types [#235][]
+- `IsMember` also supports container of pairs, transform allows modification of
+  result [#228][]
+- Added new Transformers, `CLI::AsNumberWithUnit` and `CLI::AsSizeValue`
+  [#253][]
+- Much more powerful flags with different values [#211][], general types
+  [#235][]
 - `add_option` now supports bool due to unified bool handling [#211][]
 - Support for composable unnamed subcommands [#216][]
 - Reparsing is better supported with `.remaining_for_passthrough()` [#265][]
 - Custom vector separator using `->delimiter(char)` [#209][], [#221][], [#240][]
-- Validators added for IP4 addresses and positive numbers [#210][] and numbers [#262][]
-- Minimum required Boost for optional Optionals has been corrected to 1.61 [#226][]
-- Positionals can stop options from being parsed with `app.positionals_at_end()` [#223][]
+- Validators added for IP4 addresses and positive numbers [#210][] and numbers
+  [#262][]
+- Minimum required Boost for optional Optionals has been corrected to 1.61
+  [#226][]
+- Positionals can stop options from being parsed with `app.positionals_at_end()`
+  [#223][]
 - Added `validate_positionals` [#262][]
-- Positional parsing is much more powerful [#251][], duplicates supported [#247][]
-- Validators can be negated with `!` [#230][], and now handle tname functions [#228][]
+- Positional parsing is much more powerful [#251][], duplicates supported
+  [#247][]
+- Validators can be negated with `!` [#230][], and now handle tname functions
+  [#228][]
 - Better enum support and streaming helper [#233][] and [#228][]
 - Cleanup for shadow warnings [#232][]
 - Better alignment on multiline descriptions [#269][]
 - Better support for aarch64 [#266][]
-- Respect `BUILD_TESTING` only if CLI11 is the main project; otherwise, `CLI11_TESTING` must be used [#277][]
-- Drop auto-detection of experimental optional and boost::optional; must be enabled explicitly (too fragile) [#277][] [#279][]
+- Respect `BUILD_TESTING` only if CLI11 is the main project; otherwise,
+  `CLI11_TESTING` must be used [#277][]
+- Drop auto-detection of experimental optional and boost::optional; must be
+  enabled explicitly (too fragile) [#277][] [#279][]
  
 > ### Converting from CLI11 1.7
 >
-> - `.add_option(..., true)` should be replaced by `.add_option(...)->capture_default_str()` or `app.option_defaults()->always_capture_default()` can be used
-> - `app.add_set("--name", value, {"choice1", "choice2"})` should become `app.add_option("--name", value)->check(CLI::IsMember({"choice1", "choice2"}))`
-> - The `_ignore_case` version of this can be replaced by adding `CLI::ignore_case` to the argument list in `IsMember`
-> - The `_ignore_underscore` version of this can be replaced by adding `CLI::ignore_underscore` to the argument list in `IsMember`
-> - The `_ignore_case_underscore` version of this can be replaced by adding both functions listed above to the argument list in `IsMember`
-> - If you want an exact match to the original choice after one of the modifier functions matches, use `->transform` instead of `->check`
-> - The `_mutable` versions of this can be replaced by passing a pointer or shared pointer into `IsMember`
-> - An error with sets now produces a `ValidationError` instead of a `ConversionError`
+> - `.add_option(..., true)` should be replaced by
+>   `.add_option(...)->capture_default_str()` or
+>   `app.option_defaults()->always_capture_default()` can be used
+> - `app.add_set("--name", value, {"choice1", "choice2"})` should become
+>   `app.add_option("--name", value)->check(CLI::IsMember({"choice1", "choice2"}))`
+> - The `_ignore_case` version of this can be replaced by adding
+>   `CLI::ignore_case` to the argument list in `IsMember`
+> - The `_ignore_underscore` version of this can be replaced by adding
+>   `CLI::ignore_underscore` to the argument list in `IsMember`
+> - The `_ignore_case_underscore` version of this can be replaced by adding both
+>   functions listed above to the argument list in `IsMember`
+> - If you want an exact match to the original choice after one of the modifier
+>   functions matches, use `->transform` instead of `->check`
+> - The `_mutable` versions of this can be replaced by passing a pointer or
+>   shared pointer into `IsMember`
+> - An error with sets now produces a `ValidationError` instead of a
+>   `ConversionError`
  
 [#209]: https://github.com/CLIUtils/CLI11/pull/209
 [#210]: https://github.com/CLIUtils/CLI11/pull/210
@@ -321,29 +403,50 @@ Set handling has been completely replaced by a new backend that works as a Valid
  
 ## Version 1.7: Parse breakup
  
-The parsing procedure now maps much more sensibly to complex, nested subcommand structures. Each phase of the parsing happens on all subcommands before moving on with the next phase of the parse. This allows several features, like required environment variables, to work properly even through subcommand boundaries.
-Passing the same subcommand multiple times is better supported. Several new features were added as well, including Windows style option support, parsing strings directly, and ignoring underscores in names. Adding a set that you plan to change later must now be done with `add_mutable_set`.
-
-- Support Windows style options with `->allow_windows_style_options`. [#187][] On by default on Windows. [#190][]
-- Added `parse(string)` to split up and parse a command-line style string directly. [#186][]
-- Added `ignore_underscore` and related functions, to ignore underscores when matching names. [#185][]
+The parsing procedure now maps much more sensibly to complex, nested subcommand
+structures. Each phase of the parsing happens on all subcommands before moving
+on with the next phase of the parse. This allows several features, like required
+environment variables, to work properly even through subcommand boundaries.
+Passing the same subcommand multiple times is better supported. Several new
+features were added as well, including Windows style option support, parsing
+strings directly, and ignoring underscores in names. Adding a set that you plan
+to change later must now be done with `add_mutable_set`.
+
+- Support Windows style options with `->allow_windows_style_options`. [#187][]
+  On by default on Windows. [#190][]
+- Added `parse(string)` to split up and parse a command-line style string
+  directly. [#186][]
+- Added `ignore_underscore` and related functions, to ignore underscores when
+  matching names. [#185][]
 - The default INI Config will now add quotes to strings with spaces [#195][]
-- The default message now will mention the help-all flag also if present [#197][]
+- The default message now will mention the help-all flag also if present
+  [#197][]
 - Added `->description` to set Option descriptions [#199][]
-- Mutating sets (introduced in Version 1.6) now have a clear add method, `add_mutable_set*`, since the set reference should not expire [#200][]
-- Subcommands now track how many times they were parsed in a parsing process. `count()` with no arguments will return the number of times a subcommand was encountered. [#178][]
-- Parsing is now done in phases: `shortcurcuits`, `ini`, `env`, `callbacks`, and `requirements`; all subcommands complete a phase before moving on. [#178][]
-- Calling parse multiple times is now officially supported without `clear` (automatic). [#178][]
-- Dropped the mostly undocumented `short_circuit` property, as help flag parsing is a bit more complex, and the default callback behavior of options now works properly. [#179][]
+- Mutating sets (introduced in Version 1.6) now have a clear add method,
+  `add_mutable_set*`, since the set reference should not expire [#200][]
+- Subcommands now track how many times they were parsed in a parsing process.
+  `count()` with no arguments will return the number of times a subcommand was
+  encountered. [#178][]
+- Parsing is now done in phases: `shortcurcuits`, `ini`, `env`, `callbacks`, and
+  `requirements`; all subcommands complete a phase before moving on. [#178][]
+- Calling parse multiple times is now officially supported without `clear`
+  (automatic). [#178][]
+- Dropped the mostly undocumented `short_circuit` property, as help flag parsing
+  is a bit more complex, and the default callback behavior of options now works
+  properly. [#179][]
 - Use the standard `BUILD_TESTING` over `CLI11_TESTING` if defined [#183][]
 - Cleanup warnings [#191][]
-- Remove deprecated names: `set_footer`, `set_name`, `set_callback`, and `set_type_name`. Use without the `set_` instead. [#192][]
+- Remove deprecated names: `set_footer`, `set_name`, `set_callback`, and
+  `set_type_name`. Use without the `set_` instead. [#192][]
  
 > ### Converting from CLI11 1.6
 >
-> - `->short_circuit()` is no longer needed, just remove it if you were using it - raising an exception will happen in the proper place now without it.
-> - `->add_set*` becomes `->add_mutable_set*` if you were using the editable set feature
-> - `footer`, `name`, `callback`, and `type_name` must be used instead of the `set_*` versions (deprecated previously).
+> - `->short_circuit()` is no longer needed, just remove it if you were using
+>   it - raising an exception will happen in the proper place now without it.
+> - `->add_set*` becomes `->add_mutable_set*` if you were using the editable set
+>   feature
+> - `footer`, `name`, `callback`, and `type_name` must be used instead of the
+>   `set_*` versions (deprecated previously).
  
 [#178]: https://github.com/CLIUtils/CLI11/pull/178
 [#183]: https://github.com/CLIUtils/CLI11/pull/183
@@ -360,7 +463,8 @@ Passing the same subcommand multiple times is better supported. Several new feat
  
 ### Version 1.7.1: Quick patch
  
-This version provides a quick patch for a (correct) warning from GCC 8 for the windows options code.
+This version provides a quick patch for a (correct) warning from GCC 8 for the
+windows options code.
  
 - Fix for Windows style option parsing [#201][]
 - Improve `add_subcommand` when throwing an exception [#204][]
@@ -372,7 +476,9 @@ This version provides a quick patch for a (correct) warning from GCC 8 for the w
  
 ## Version 1.6: Formatting help
  
-Added a new formatting system [#109][]. You can now set the formatter on Apps. This has also simplified the internals of Apps and Options a bit by separating most formatting code.
+Added a new formatting system [#109][]. You can now set the formatter on Apps.
+This has also simplified the internals of Apps and Options a bit by separating
+most formatting code.
  
 - Added `CLI::Formatter` and `formatter` slot for apps, inherited.
 - `FormatterBase` is the minimum required.
@@ -387,7 +493,8 @@ Changes to the help system (most normal users will not notice this):
 - Removed `help_*` functions.
 - Protected function `_has_help_positional` removed.
 - `format_help` can now be chained.
-- Added getters for the missing parts of options (help no longer uses any private parts).
+- Added getters for the missing parts of options (help no longer uses any
+  private parts).
 - Help flags now use new `short_circuit` property to simplify parsing. [#121][]
  
 New for Config file reading and writing [#121][]:
@@ -400,7 +507,8 @@ New for Config file reading and writing [#121][]:
 - Added `ConfigItem`.
 - Added an example of a custom config format using [nlohmann/json][]. [#138][]
  
-Validators are now much more powerful [#118][], all built in validators upgraded to the new form:
+Validators are now much more powerful [#118][], all built in validators upgraded
+to the new form:
  
 - A subclass of `CLI::Validator` is now also accepted.
 - They now can set the type name to things like `PATH` and `INT in [1-4]`.
@@ -410,24 +518,32 @@ Validators are now much more powerful [#118][], all built in validators upgraded
 Other changes:
  
 - Fixing `parse(args)`'s `args` setting and ordering after parse. [#141][]
-- Replaced `set_custom_option` with `type_name` and `type_size` instead of `set_custom_option`. Methods return `this`. [#136][]
-- Dropped `set_` on Option's `type_name`, `default_str`, and `default_val`. [#136][]
-- Removed `set_` from App's `failure_message`, `footer`, `callback`, and `name`. [#136][]
+- Replaced `set_custom_option` with `type_name` and `type_size` instead of
+  `set_custom_option`. Methods return `this`. [#136][]
+- Dropped `set_` on Option's `type_name`, `default_str`, and `default_val`.
+  [#136][]
+- Removed `set_` from App's `failure_message`, `footer`, `callback`, and `name`.
+  [#136][]
 - Fixed support `N<-1` for `type_size`. [#140][]
 - Added `->each()` to make adding custom callbacks easier. [#126][]
-- Allow empty options `add_option("-n",{})` to be edited later with `each` [#142][]
-- Added filter argument to `get_subcommands`, `get_options`; use empty filter `{}` to avoid filtering.
+- Allow empty options `add_option("-n",{})` to be edited later with `each`
+  [#142][]
+- Added filter argument to `get_subcommands`, `get_options`; use empty filter
+  `{}` to avoid filtering.
 - Added `get_groups()` to get groups.
-- Better support for manual options with `get_option`, `set_results`, and `empty`. [#119][]
+- Better support for manual options with `get_option`, `set_results`, and
+  `empty`. [#119][]
 - `lname` and `sname` have getters, added `const get_parent`. [#120][]
-- Using `add_set` will now capture L-values for sets, allowing further modification. [#113][]
+- Using `add_set` will now capture L-values for sets, allowing further
+  modification. [#113][]
 - Dropped duplicate way to run `get_type_name` (`get_typeval`).
 - Removed `requires` in favor of `needs` (deprecated in last version). [#112][]
 - Const added to argv. [#126][]
  
 Backend and testing changes:
  
-- Internally, `type_name` is now a lambda function; for sets, this reads the set live. [#116][]
+- Internally, `type_name` is now a lambda function; for sets, this reads the set
+  live. [#116][]
 - Cleaner tests without `app.reset()` (and `reset` is now `clear`). [#141][]
 - Better CMake policy handling. [#110][]
 - Includes are properly sorted. [#120][]
@@ -453,12 +569,14 @@ Backend and testing changes:
  
 ### Version 1.6.1: Platform fixes
  
-This version provides a few fixes for special cases, such as mixing with `Windows.h` and better defaults
-for systems like Hunter. The one new feature is the ability to produce "branded" single file output for
-providing custom namespaces or custom macro names.
+This version provides a few fixes for special cases, such as mixing with
+`Windows.h` and better defaults for systems like Hunter. The one new feature is
+the ability to produce "branded" single file output for providing custom
+namespaces or custom macro names.
  
 - Added fix and test for including Windows.h [#145][]
-- No longer build single file by default if main project, supports systems stuck on Python 2.6 [#149][], [#151][]
+- No longer build single file by default if main project, supports systems stuck
+  on Python 2.6 [#149][], [#151][]
 - Branding support for single file output [#150][]
  
 [#145]: https://github.com/CLIUtils/CLI11/pull/145
@@ -468,18 +586,22 @@ providing custom namespaces or custom macro names.
  
 ### Version 1.6.2: Help-all
  
-This version fixes some formatting bugs with help-all. It also adds fixes for several warnings, including an experimental optional error on Clang 7. Several smaller fixes.
+This version fixes some formatting bugs with help-all. It also adds fixes for
+several warnings, including an experimental optional error on Clang 7. Several
+smaller fixes.
  
 - Fixed help-all formatting [#163][]
   - Printing help-all on nested command now fixed (App)
   - Missing space after help-all restored (Default formatter)
   - More detail printed on help all (Default formatter)
-  - Help-all subcommands get indented with inner blank lines removed (Default formatter)
+  - Help-all subcommands get indented with inner blank lines removed (Default
+    formatter)
   - `detail::find_and_replace` added to utilities
 - Fixed CMake install as subproject with `CLI11_INSTALL` flag. [#156][]
 - Fixed warning about local variable hiding class member with MSVC [#157][]
 - Fixed compile error with default settings on Clang 7 and libc++ [#158][]
-- Fixed special case of `--help` on subcommands (general fix planned for 1.7) [#168][]
+- Fixed special case of `--help` on subcommands (general fix planned for 1.7)
+  [#168][]
 - Removing an option with links [#179][]
  
 [#156]: https://github.com/CLIUtils/CLI11/issues/156
@@ -491,15 +613,24 @@ This version fixes some formatting bugs with help-all. It also adds fixes for se
  
 ## Version 1.5: Optionals
  
-This version introduced support for optionals, along with clarification and examples of custom conversion overloads. Enums now have been dropped from the automatic conversion system, allowing explicit protection for out-of-range ints (or a completely custom conversion). This version has some internal cleanup and improved support for the newest compilers. Several bugs were fixed, as well.
+This version introduced support for optionals, along with clarification and
+examples of custom conversion overloads. Enums now have been dropped from the
+automatic conversion system, allowing explicit protection for out-of-range ints
+(or a completely custom conversion). This version has some internal cleanup and
+improved support for the newest compilers. Several bugs were fixed, as well.
  
 Note: This is the final release with `requires`, please switch to `needs`.
  
-- Fix unlimited short options eating two values before checking for positionals when no space present [#90][]
-- Symmetric exclude text when excluding options, exclude can be called multiple times [#64][]
-- Support for `std::optional`, `std::experimental::optional`, and `boost::optional` added if `__has_include` is supported [#95][]
-- All macros/CMake variables now start with `CLI11_` instead of just `CLI_` [#95][]
-- The internal stream was not being cleared before use in some cases. Fixed. [#95][]
+- Fix unlimited short options eating two values before checking for positionals
+  when no space present [#90][]
+- Symmetric exclude text when excluding options, exclude can be called multiple
+  times [#64][]
+- Support for `std::optional`, `std::experimental::optional`, and
+  `boost::optional` added if `__has_include` is supported [#95][]
+- All macros/CMake variables now start with `CLI11_` instead of just `CLI_`
+  [#95][]
+- The internal stream was not being cleared before use in some cases. Fixed.
+  [#95][]
 - Using an enum now requires explicit conversion overload [#97][]
 - The separator `--` now is removed when it ends unlimited arguments [#100][]
  
@@ -510,8 +641,10 @@ Other, non-user facing changes:
 - C++17 is now tested on supported platforms [#95][]
 - Informational printout now added to CTest [#95][]
 - Better single file generation [#95][]
-- Added support for GTest on MSVC 2017 (but not in C++17 mode, will need next version of GTest)
-- Types now have a specific size, separate from the expected number - cleaner and more powerful internally [#92][]
+- Added support for GTest on MSVC 2017 (but not in C++17 mode, will need next
+  version of GTest)
+- Types now have a specific size, separate from the expected number - cleaner
+  and more powerful internally [#92][]
 - Examples now run as part of testing [#99][]
  
 [#64]: https://github.com/CLIUtils/CLI11/issues/64
@@ -524,11 +657,15 @@ Other, non-user facing changes:
  
 ### Version 1.5.1: Access
  
-This patch release adds better access to the App programmatically, to assist with writing custom converters to other formats. It also improves the help output, and uses a new feature in CLI11 1.5 to fix an old "quirk" in the way unlimited options and positionals interact.
+This patch release adds better access to the App programmatically, to assist
+with writing custom converters to other formats. It also improves the help
+output, and uses a new feature in CLI11 1.5 to fix an old "quirk" in the way
+unlimited options and positionals interact.
  
 - Make mixing unlimited positionals and options more intuitive [#102][]
 - Add missing getters `get_options` and `get_description` to App [#105][]
-- The app name now can be set, and will override the auto name if present [#105][]
+- The app name now can be set, and will override the auto name if present
+  [#105][]
 - Add `(REQUIRED)` for required options [#104][]
 - Print simple name for Needs/Excludes [#104][]
 - Use Needs instead of Requires in help print [#104][]
@@ -541,21 +678,30 @@ This patch release adds better access to the App programmatically, to assist wit
  
 ### Version 1.5.2: LICENSE in single header mode
  
-This is a quick patch release that makes LICENSE part of the single header file, making it easier to include. Minor cleanup from codacy. No significant code changes from 1.5.1.
+This is a quick patch release that makes LICENSE part of the single header file,
+making it easier to include. Minor cleanup from codacy. No significant code
+changes from 1.5.1.
  
 ### Version 1.5.3: Compiler compatibility
  
-This version fixes older AppleClang compilers by removing the optimization for casting. The minimum version of Boost Optional supported has been clarified to be 1.58. CUDA 7.0 NVCC is now supported.
+This version fixes older AppleClang compilers by removing the optimization for
+casting. The minimum version of Boost Optional supported has been clarified to
+be 1.58. CUDA 7.0 NVCC is now supported.
  
 ### Version 1.5.4: Optionals
  
-This version fixes the optional search in the single file version; some macros were not yet defined when it did the search. You can define the `CLI11_*_OPTIONAL` macros to 0 if needed to eliminate the search.
+This version fixes the optional search in the single file version; some macros
+were not yet defined when it did the search. You can define the
+`CLI11_*_OPTIONAL` macros to 0 if needed to eliminate the search.
  
 ## Version 1.4: More feedback
  
-This version adds lots of smaller fixes and additions after the refactor in version 1.3. More ways to download and use CLI11 in CMake have been added. INI files have improved support.
+This version adds lots of smaller fixes and additions after the refactor in
+version 1.3. More ways to download and use CLI11 in CMake have been added. INI
+files have improved support.
  
-- Lexical cast is now more strict than before [#68][] and fails on overflow [#84][]
+- Lexical cast is now more strict than before [#68][] and fails on overflow
+  [#84][]
 - Added `get_parent()` to access the parent from a subcommand
 - Added `ExistingPath` validator [#73][]
 - `app.allow_ini_extras()` added to allow extras in INI files [#70][]
@@ -564,7 +710,8 @@ This version adds lots of smaller fixes and additions after the refactor in vers
 - Double printing of error message fixed [#77][]
 - Renamed `requires` to `needs` to avoid C++20 keyword [#75][], [#82][]
 - MakeSingleHeader now works if outside of git [#78][]
-- Adding install support for CMake [#79][], improved support for `find_package` [#83][], [#84][]
+- Adding install support for CMake [#79][], improved support for `find_package`
+  [#83][], [#84][]
 - Added support for Conan.io [#83][]
  
 [#70]: https://github.com/CLIUtils/CLI11/issues/70
@@ -581,73 +728,128 @@ This version adds lots of smaller fixes and additions after the refactor in vers
  
 ## Version 1.3: Refactor
  
-This version focused on refactoring several key systems to ensure correct behavior in the interaction of different settings. Most caveats about
-features only working on the main App have been addressed, and extra arguments have been reworked. Inheritance
-of defaults makes configuring CLI11 much easier without having to subclass. Policies add new ways to handle multiple arguments to match your
-favorite CLI programs. Error messages and help messages are better and more flexible. Several bugs and odd behaviors in the parser have been fixed.
-
-- Added a version macro, `CLI11_VERSION`, along with `*_MAJOR`, `*_MINOR`, and `*_PATCH`, for programmatic access to the version.
-- Reworked the way defaults are set and inherited; explicit control given to user with `->option_defaults()` [#48](https://github.com/CLIUtils/CLI11/pull/48)
-- Hidden options now are based on an empty group name, instead of special "hidden" keyword [#48](https://github.com/CLIUtils/CLI11/pull/48)
-- `parse` no longer returns (so `CLI11_PARSE` is always usable) [#37](https://github.com/CLIUtils/CLI11/pull/37)
-- Added `remaining()` and `remaining_size()` [#37](https://github.com/CLIUtils/CLI11/pull/37)
-- `allow_extras` and `prefix_command` are now valid on subcommands [#37](https://github.com/CLIUtils/CLI11/pull/37)
-- Added `take_last` to only take last value passed [#40](https://github.com/CLIUtils/CLI11/pull/40)
-- Added `multi_option_policy` and shortcuts to provide more control than just a take last policy [#59](https://github.com/CLIUtils/CLI11/pull/59)
-- More detailed error messages in a few cases [#41](https://github.com/CLIUtils/CLI11/pull/41)
+This version focused on refactoring several key systems to ensure correct
+behavior in the interaction of different settings. Most caveats about features
+only working on the main App have been addressed, and extra arguments have been
+reworked. Inheritance of defaults makes configuring CLI11 much easier without
+having to subclass. Policies add new ways to handle multiple arguments to match
+your favorite CLI programs. Error messages and help messages are better and more
+flexible. Several bugs and odd behaviors in the parser have been fixed.
+
+- Added a version macro, `CLI11_VERSION`, along with `*_MAJOR`, `*_MINOR`, and
+  `*_PATCH`, for programmatic access to the version.
+- Reworked the way defaults are set and inherited; explicit control given to
+  user with `->option_defaults()`
+  [#48](https://github.com/CLIUtils/CLI11/pull/48)
+- Hidden options now are based on an empty group name, instead of special
+  "hidden" keyword [#48](https://github.com/CLIUtils/CLI11/pull/48)
+- `parse` no longer returns (so `CLI11_PARSE` is always usable)
+  [#37](https://github.com/CLIUtils/CLI11/pull/37)
+- Added `remaining()` and `remaining_size()`
+  [#37](https://github.com/CLIUtils/CLI11/pull/37)
+- `allow_extras` and `prefix_command` are now valid on subcommands
+  [#37](https://github.com/CLIUtils/CLI11/pull/37)
+- Added `take_last` to only take last value passed
+  [#40](https://github.com/CLIUtils/CLI11/pull/40)
+- Added `multi_option_policy` and shortcuts to provide more control than just a
+  take last policy [#59](https://github.com/CLIUtils/CLI11/pull/59)
+- More detailed error messages in a few cases
+  [#41](https://github.com/CLIUtils/CLI11/pull/41)
 - Footers can be added to help [#42](https://github.com/CLIUtils/CLI11/pull/42)
-- Help flags are easier to customize [#43](https://github.com/CLIUtils/CLI11/pull/43)
+- Help flags are easier to customize
+  [#43](https://github.com/CLIUtils/CLI11/pull/43)
 - Subcommand now support groups [#46](https://github.com/CLIUtils/CLI11/pull/46)
-- `CLI::RuntimeError` added, for easy exit with error codes [#45](https://github.com/CLIUtils/CLI11/pull/45)
-- The clang-format script is now no longer "hidden" [#48](https://github.com/CLIUtils/CLI11/pull/48)
-- The order is now preserved for subcommands (list and callbacks) [#49](https://github.com/CLIUtils/CLI11/pull/49)
-- Tests now run individually, utilizing CMake 3.10 additions if possible [#50](https://github.com/CLIUtils/CLI11/pull/50)
-- Failure messages are now customizable, with a shorter default [#52](https://github.com/CLIUtils/CLI11/pull/52)
-- Some improvements to error codes [#53](https://github.com/CLIUtils/CLI11/pull/53)
-- `require_subcommand` now offers a two-argument form and negative values on the one-argument form are more useful [#51](https://github.com/CLIUtils/CLI11/pull/51)
-- Subcommands no longer match after the max required number is obtained [#51](https://github.com/CLIUtils/CLI11/pull/51)
-- Unlimited options no longer prioritize over remaining/unlimited positionals [#51](https://github.com/CLIUtils/CLI11/pull/51)
-- Added `->transform` which modifies the string parsed [#54](https://github.com/CLIUtils/CLI11/pull/54)
-- Changed of API in validators to `void(std::string &)` (const for users), throwing providing nicer errors [#54](https://github.com/CLIUtils/CLI11/pull/54)
-- Added `CLI::ArgumentMismatch` [#56](https://github.com/CLIUtils/CLI11/pull/56) and fixed missing failure if one arg expected [#55](https://github.com/CLIUtils/CLI11/issues/55)
-- Support for minimum unlimited expected arguments [#56](https://github.com/CLIUtils/CLI11/pull/56)
-- Single internal arg parse function [#56](https://github.com/CLIUtils/CLI11/pull/56)
-- Allow options to be disabled from INI file, rename `add_config` to `set_config` [#60](https://github.com/CLIUtils/CLI11/pull/60)
+- `CLI::RuntimeError` added, for easy exit with error codes
+  [#45](https://github.com/CLIUtils/CLI11/pull/45)
+- The clang-format script is now no longer "hidden"
+  [#48](https://github.com/CLIUtils/CLI11/pull/48)
+- The order is now preserved for subcommands (list and callbacks)
+  [#49](https://github.com/CLIUtils/CLI11/pull/49)
+- Tests now run individually, utilizing CMake 3.10 additions if possible
+  [#50](https://github.com/CLIUtils/CLI11/pull/50)
+- Failure messages are now customizable, with a shorter default
+  [#52](https://github.com/CLIUtils/CLI11/pull/52)
+- Some improvements to error codes
+  [#53](https://github.com/CLIUtils/CLI11/pull/53)
+- `require_subcommand` now offers a two-argument form and negative values on the
+  one-argument form are more useful
+  [#51](https://github.com/CLIUtils/CLI11/pull/51)
+- Subcommands no longer match after the max required number is obtained
+  [#51](https://github.com/CLIUtils/CLI11/pull/51)
+- Unlimited options no longer prioritize over remaining/unlimited positionals
+  [#51](https://github.com/CLIUtils/CLI11/pull/51)
+- Added `->transform` which modifies the string parsed
+  [#54](https://github.com/CLIUtils/CLI11/pull/54)
+- Changed of API in validators to `void(std::string &)` (const for users),
+  throwing providing nicer errors
+  [#54](https://github.com/CLIUtils/CLI11/pull/54)
+- Added `CLI::ArgumentMismatch` [#56](https://github.com/CLIUtils/CLI11/pull/56)
+  and fixed missing failure if one arg expected
+  [#55](https://github.com/CLIUtils/CLI11/issues/55)
+- Support for minimum unlimited expected arguments
+  [#56](https://github.com/CLIUtils/CLI11/pull/56)
+- Single internal arg parse function
+  [#56](https://github.com/CLIUtils/CLI11/pull/56)
+- Allow options to be disabled from INI file, rename `add_config` to
+  `set_config` [#60](https://github.com/CLIUtils/CLI11/pull/60)
  
 > ### Converting from CLI11 1.2
 >
 > - `app.parse` no longer returns a vector. Instead, use `app.remaining(true)`.
 > - `"hidden"` is no longer a special group name, instead use `""`
-> - Validators API has changed to return an error string; use `.empty()` to get the old bool back
-> - Use `.set_help_flag` instead of accessing the help pointer directly (discouraged, but not removed yet)
+> - Validators API has changed to return an error string; use `.empty()` to get
+>   the old bool back
+> - Use `.set_help_flag` instead of accessing the help pointer directly
+>   (discouraged, but not removed yet)
 > - `add_config` has been renamed to `set_config`
 > - Errors thrown in some cases are slightly more specific
  
 ## Version 1.2: Stability
  
-This release focuses on making CLI11 behave properly in corner cases, and with config files on the command line. This includes fixes for a variety of reported issues. A few features were added to make life easier, as well; such as a new flag callback and a macro for the parse command.
-
-- Added functional form of flag [#33](https://github.com/CLIUtils/CLI11/pull/33), automatic on C++14
-- Fixed Config file search if passed on command line [#30](https://github.com/CLIUtils/CLI11/issues/30)
-- Added `CLI11_PARSE(app, argc, argv)` macro for simple parse commands (does not support returning arg)
-- The name string can now contain spaces around commas [#29](https://github.com/CLIUtils/CLI11/pull/29)
-- `set_default_str` now only sets string, and `set_default_val` will evaluate the default string given [#26](https://github.com/CLIUtils/CLI11/issues/26)
-- Required positionals now take priority over subcommands [#23](https://github.com/CLIUtils/CLI11/issues/23)
+This release focuses on making CLI11 behave properly in corner cases, and with
+config files on the command line. This includes fixes for a variety of reported
+issues. A few features were added to make life easier, as well; such as a new
+flag callback and a macro for the parse command.
+
+- Added functional form of flag
+  [#33](https://github.com/CLIUtils/CLI11/pull/33), automatic on C++14
+- Fixed Config file search if passed on command line
+  [#30](https://github.com/CLIUtils/CLI11/issues/30)
+- Added `CLI11_PARSE(app, argc, argv)` macro for simple parse commands (does not
+  support returning arg)
+- The name string can now contain spaces around commas
+  [#29](https://github.com/CLIUtils/CLI11/pull/29)
+- `set_default_str` now only sets string, and `set_default_val` will evaluate
+  the default string given [#26](https://github.com/CLIUtils/CLI11/issues/26)
+- Required positionals now take priority over subcommands
+  [#23](https://github.com/CLIUtils/CLI11/issues/23)
 - Extra requirements enforced by Travis
  
 ## Version 1.1: Feedback
  
-This release incorporates feedback from the release announcement. The examples are slowly being expanded, some corner cases improved, and some new functionality for tricky parsing situations.
-
-- Added simple support for enumerations, allow non-printable objects [#12](https://github.com/CLIUtils/CLI11/issues/12)
-- Added `app.parse_order()` with original parse order ([#13](https://github.com/CLIUtils/CLI11/issues/13), [#16](https://github.com/CLIUtils/CLI11/pull/16))
-- Added `prefix_command()`, which is like `allow_extras` but instantly stops and returns. ([#8](https://github.com/CLIUtils/CLI11/issues/8), [#17](https://github.com/CLIUtils/CLI11/pull/17))
-- Removed Windows warning ([#10](https://github.com/CLIUtils/CLI11/issues/10), [#20](https://github.com/CLIUtils/CLI11/pull/20))
-- Some improvements to CMake, detect Python and no dependencies on Python 2 (like Python 3) ([#18](https://github.com/CLIUtils/CLI11/issues/18), [#21](https://github.com/CLIUtils/CLI11/pull/21))
+This release incorporates feedback from the release announcement. The examples
+are slowly being expanded, some corner cases improved, and some new
+functionality for tricky parsing situations.
+
+- Added simple support for enumerations, allow non-printable objects
+  [#12](https://github.com/CLIUtils/CLI11/issues/12)
+- Added `app.parse_order()` with original parse order
+  ([#13](https://github.com/CLIUtils/CLI11/issues/13),
+  [#16](https://github.com/CLIUtils/CLI11/pull/16))
+- Added `prefix_command()`, which is like `allow_extras` but instantly stops and
+  returns. ([#8](https://github.com/CLIUtils/CLI11/issues/8),
+  [#17](https://github.com/CLIUtils/CLI11/pull/17))
+- Removed Windows warning ([#10](https://github.com/CLIUtils/CLI11/issues/10),
+  [#20](https://github.com/CLIUtils/CLI11/pull/20))
+- Some improvements to CMake, detect Python and no dependencies on Python 2
+  (like Python 3) ([#18](https://github.com/CLIUtils/CLI11/issues/18),
+  [#21](https://github.com/CLIUtils/CLI11/pull/21))
  
 ## Version 1.0: Official release
  
-This is the first stable release for CLI11. Future releases will try to remain backward compatible and will follow semantic versioning if possible. There were a few small changes since version 0.9:
+This is the first stable release for CLI11. Future releases will try to remain
+backward compatible and will follow semantic versioning if possible. There were
+a few small changes since version 0.9:
  
 - Cleanup using `clang-tidy` and `clang-format`
 - Small improvements to Timers, easier to subclass Error
@@ -655,13 +857,16 @@ This is the first stable release for CLI11. Future releases will try to remain b
  
 ## Version 0.9: Polish
  
-This release focused on cleaning up the most exotic compiler warnings, fixing a few oddities of the config parser, and added a more natural method to check subcommands.
+This release focused on cleaning up the most exotic compiler warnings, fixing a
+few oddities of the config parser, and added a more natural method to check
+subcommands.
  
 - Better CMake named target (CLI11)
 - More warnings added, fixed
 - Ini output now includes `=false` when `default_also` is true
 - Ini no longer lists the help pointer
-- Added test for inclusion in multiple files and linking, fixed issues (rarely needed for CLI, but nice for tools)
+- Added test for inclusion in multiple files and linking, fixed issues (rarely
+  needed for CLI, but nice for tools)
 - Support for complex numbers
 - Subcommands now test true/false directly or with `->parsed()`, cleaner parse
  
@@ -674,20 +879,25 @@ This release moved the repository to the CLIUtils main organization.
  
 ## Version 0.7: Code coverage 100%
  
-Lots of small bugs fixed when adding code coverage, better in edge cases. Much more powerful ini support.
+Lots of small bugs fixed when adding code coverage, better in edge cases. Much
+more powerful ini support.
  
 - Allow comments in ini files (lines starting with `;`)
 - Ini files support flags, vectors, subcommands
 - Added CodeCov code coverage reports
 - Lots of small bugfixes related to adding tests to increase coverage to 100%
 - Error handling now uses scoped enum in errors
-- Reparsing rules changed a little to accommodate Ini files. Callbacks are now called when parsing INI, and reset any time results are added.
-- Adding extra utilities in full version only, `Timer` (not needed for parsing, but useful for general CLI applications).
+- Reparsing rules changed a little to accommodate Ini files. Callbacks are now
+  called when parsing INI, and reset any time results are added.
+- Adding extra utilities in full version only, `Timer` (not needed for parsing,
+  but useful for general CLI applications).
 - Better support for custom `add_options` like functions.
  
 ## Version 0.6: Cleanup
  
-Lots of cleanup and docs additions made it into this release. Parsing is simpler and more robust; fall through option added and works as expected; much more consistent variable names internally.
+Lots of cleanup and docs additions made it into this release. Parsing is simpler
+and more robust; fall through option added and works as expected; much more
+consistent variable names internally.
  
 - Simplified parsing to use `vector<string>` only
 - Fixed fallthrough, made it optional as well (default: off): `.fallthrough()`.
@@ -698,11 +908,20 @@ Lots of cleanup and docs additions made it into this release. Parsing is simpler
 ## Version 0.5: Windows support
  
 - Allow `Hidden` options.
-- Throw `OptionAlreadyAdded` errors for matching subcommands or options, with ignore-case included, tests
-- `->ignore_case()` added to subcommands, options, and `add_set_ignore_case`. Subcommands inherit setting from parent App on creation.
-- Subcommands now can be "chained", that is, left over arguments can now include subcommands that then get parsed. Subcommands are now a list (`get_subcommands`). Added `got_subcommand(App_or_name)` to check for subcommands.
-- Added `.allow_extras()` to disable error on failure. Parse returns a vector of leftover options. Renamed error to `ExtrasError`, and now triggers on extra options too.
-- Added `require_subcommand` to `App`, to simplify forcing subcommands. Do **not** do `add_subcommand()->require_subcommand`, since that is the subcommand, not the main `App`.
+- Throw `OptionAlreadyAdded` errors for matching subcommands or options, with
+  ignore-case included, tests
+- `->ignore_case()` added to subcommands, options, and `add_set_ignore_case`.
+  Subcommands inherit setting from parent App on creation.
+- Subcommands now can be "chained", that is, left over arguments can now include
+  subcommands that then get parsed. Subcommands are now a list
+  (`get_subcommands`). Added `got_subcommand(App_or_name)` to check for
+  subcommands.
+- Added `.allow_extras()` to disable error on failure. Parse returns a vector of
+  leftover options. Renamed error to `ExtrasError`, and now triggers on extra
+  options too.
+- Added `require_subcommand` to `App`, to simplify forcing subcommands. Do
+  **not** do `add_subcommand()->require_subcommand`, since that is the
+  subcommand, not the main `App`.
 - Added printout of ini file text given parsed options, skips flags.
 - Support for quotes and spaces in ini files
 - Fixes to allow support for Windows (added Appveyor) (Uses `-`, not `/` syntax)
@@ -717,14 +936,16 @@ Lots of cleanup and docs additions made it into this release. Parsing is simpler
  
 ## Version 0.3: Plumbum compatibility
  
-- Added `->requires`, `->excludes`, and `->envname` from [Plumbum](http://plumbum.readthedocs.io/en/latest/)
+- Added `->requires`, `->excludes`, and `->envname` from
+  [Plumbum](http://plumbum.readthedocs.io/en/latest/)
 - Supports `->mandatory` from Plumbum
 - More tests for help strings, improvements in formatting
 - Support type and set syntax in positionals help strings
 - Added help groups, with `->group("name")` syntax
 - Added initial support for ini file reading with `add_config` option.
 - Supports GCC 4.7 again
-- Clang 3.5 now required for tests due to googlemock usage, 3.4 should still work otherwise
+- Clang 3.5 now required for tests due to googlemock usage, 3.4 should still
+  work otherwise
 - Changes `setup` for an explicit help bool in constructor/`add_subcommand`
  
 ## Version 0.2: Leaner and meaner
@@ -739,4 +960,5 @@ Lots of cleanup and docs additions made it into this release. Parsing is simpler
  
 ## Version 0.1: First release
  
-First release before major cleanup. Still has make syntax and combiners; very clever syntax but not the best or most commonly expected way to work.
+First release before major cleanup. Still has make syntax and combiners; very
+clever syntax but not the best or most commonly expected way to work.
@@ -7,8 +7,7 @@
 [![Build Status AppVeyor][appveyor-badge]][appveyor]
 [![Code Coverage][codecov-badge]][codecov]
 [![Codacy Badge][codacy-badge]][codacy-link]
-[![License: BSD][license-badge]](./LICENSE)
-[![DOI][doi-badge]][doi-link]
+[![License: BSD][license-badge]](./LICENSE) [![DOI][doi-badge]][doi-link]
  
 [![Gitter chat][gitter-badge]][gitter]
 [![Latest GHA release][releases-badge]][github releases]
@@ -17,11 +16,11 @@
 [![Conda Version][conda-badge]][conda-link]
 [![Try CLI11 2.1 online][wandbox-badge]][wandbox-link]
  
-[What's new](./CHANGELOG.md) •
-[Documentation][gitbook] •
-[API Reference][api-docs]
+[What's new](./CHANGELOG.md) • [Documentation][gitbook] • [API
+Reference][api-docs]
  
-CLI11 is a command line parser for C++11 and beyond that provides a rich feature set with a simple and intuitive interface.
+CLI11 is a command line parser for C++11 and beyond that provides a rich feature
+set with a simple and intuitive interface.
  
 ## Table of Contents
  
@@ -58,35 +57,58 @@ CLI11 is a command line parser for C++11 and beyond that provides a rich feature
 - [Contribute](#contribute)
 - [License](#license)
  
-Features that were added in the last released minor version are marked with "🆕". Features only available in main are marked with "🚧".
+Features that were added in the last released minor version are marked with
+"🆕". Features only available in main are marked with "🚧".
  
 ## Background
  
 ### Introduction
  
-CLI11 provides all the features you expect in a powerful command line parser, with a beautiful, minimal syntax and no dependencies beyond C++11. It is header only, and comes in a single file form for easy inclusion in projects. It is easy to use for small projects, but powerful enough for complex command line projects, and can be customized for frameworks.
-It is tested on [Azure][] and [GitHub Actions][actions-link], and was originally used by the [GooFit GPU fitting framework][goofit]. It was inspired by [`plumbum.cli`][plumbum] for Python. CLI11 has a user friendly introduction in this README, a more in-depth tutorial [GitBook][], as well as [API documentation][api-docs] generated by Travis.
-See the [changelog](./CHANGELOG.md) or [GitHub Releases][] for details for current and past releases. Also see the [Version 1.0 post][], [Version 1.3 post][], [Version 1.6 post][], or [Version 2.0 post][] for more information.
-
-You can be notified when new releases are made by subscribing to <https://github.com/CLIUtils/CLI11/releases.atom> on an RSS reader, like Feedly, or use the releases mode of the GitHub watching tool.
+CLI11 provides all the features you expect in a powerful command line parser,
+with a beautiful, minimal syntax and no dependencies beyond C++11. It is header
+only, and comes in a single file form for easy inclusion in projects. It is easy
+to use for small projects, but powerful enough for complex command line
+projects, and can be customized for frameworks. It is tested on [Azure][] and
+[GitHub Actions][actions-link], and was originally used by the [GooFit GPU
+fitting framework][goofit]. It was inspired by [`plumbum.cli`][plumbum] for
+Python. CLI11 has a user friendly introduction in this README, a more in-depth
+tutorial [GitBook][], as well as [API documentation][api-docs] generated by
+Travis. See the [changelog](./CHANGELOG.md) or [GitHub Releases][] for details
+for current and past releases. Also see the [Version 1.0 post][], [Version 1.3
+post][], [Version 1.6 post][], or [Version 2.0 post][] for more information.
+
+You can be notified when new releases are made by subscribing to
+<https://github.com/CLIUtils/CLI11/releases.atom> on an RSS reader, like Feedly,
+or use the releases mode of the GitHub watching tool.
  
 ### Why write another CLI parser?
  
 An acceptable CLI parser library should be all of the following:
  
-- Easy to include (i.e., header only, one file if possible, **no external requirements**).
-- Short, simple syntax: This is one of the main reasons to use a CLI parser, it should make variables from the command line nearly as easy to define as any other variables. If most of your program is hidden in CLI parsing, this is a problem for readability.
-- C++11 or better: Should work with GCC 4.8+ (default on CentOS/RHEL 7), Clang 3.4+, AppleClang 7+, NVCC 7.0+, or MSVC 2015+.
+- Easy to include (i.e., header only, one file if possible, **no external
+  requirements**).
+- Short, simple syntax: This is one of the main reasons to use a CLI parser, it
+  should make variables from the command line nearly as easy to define as any
+  other variables. If most of your program is hidden in CLI parsing, this is a
+  problem for readability.
+- C++11 or better: Should work with GCC 4.8+ (default on CentOS/RHEL 7), Clang
+  3.4+, AppleClang 7+, NVCC 7.0+, or MSVC 2015+.
 - Work on Linux, macOS, and Windows.
-- Well tested on all common platforms and compilers. "Well" is defined as having good coverage measured by [CodeCov][].
+- Well tested on all common platforms and compilers. "Well" is defined as having
+  good coverage measured by [CodeCov][].
 - Clear help printing.
 - Nice error messages.
-- Standard shell idioms supported naturally, like grouping flags, a positional separator, etc.
-- Easy to execute, with help, parse errors, etc. providing correct exit and details.
+- Standard shell idioms supported naturally, like grouping flags, a positional
+  separator, etc.
+- Easy to execute, with help, parse errors, etc. providing correct exit and
+  details.
 - Easy to extend as part of a framework that provides "applications" to users.
-- Usable subcommand syntax, with support for multiple subcommands, nested subcommands, option groups, and optional fallthrough (explained later).
-- Ability to add a configuration file (`TOML`, `INI`, or custom format), and produce it as well.
-- Produce real values that can be used directly in code, not something you have pay compute time to look up, for HPC applications.
+- Usable subcommand syntax, with support for multiple subcommands, nested
+  subcommands, option groups, and optional fallthrough (explained later).
+- Ability to add a configuration file (`TOML`, `INI`, or custom format), and
+  produce it as well.
+- Produce real values that can be used directly in code, not something you have
+  pay compute time to look up, for HPC applications.
 - Work with common types, simple custom types, and extensible to exotic types.
 - Permissively licensed.
  
@@ -117,31 +139,57 @@ After I wrote this, I also found the following libraries:
 | [argparse][]            | C++17 single file argument parser. Design seems similar to CLI11 in some ways. The author has several other interesting projects.                                                    |
 | [lyra][]                | a simple header only parser with composable options. Might work well for simple standardized parsing                                                                                 |
  
-See [Awesome C++][] for a less-biased list of parsers. You can also find other single file libraries at [Single file libs][].
+See [Awesome C++][] for a less-biased list of parsers. You can also find other
+single file libraries at [Single file libs][].
  
 </p></details>
 <br/>
  
-None of these libraries fulfill all the above requirements, or really even come close. As you probably have already guessed, CLI11 does.
-So, this library was designed to provide a great syntax, good compiler compatibility, and minimal installation fuss.
+None of these libraries fulfill all the above requirements, or really even come
+close. As you probably have already guessed, CLI11 does. So, this library was
+designed to provide a great syntax, good compiler compatibility, and minimal
+installation fuss.
  
 ### Features not supported by this library
  
-There are some other possible "features" that are intentionally not supported by this library:
-
-- Non-standard variations on syntax, like `-long` options. This is non-standard and should be avoided, so that is enforced by this library.
-- Completion of partial options, such as Python's `argparse` supplies for incomplete arguments. It's better not to guess. Most third party command line parsers for python actually reimplement command line parsing rather than using argparse because of this perceived design flaw (recent versions do have an option to disable it).
-- Autocomplete: This might eventually be added to both Plumbum and CLI11, but it is not supported yet.
-- Wide strings / unicode: Since this uses the standard library only, it might be hard to properly implement, but I would be open to suggestions in how to do this.
+There are some other possible "features" that are intentionally not supported by
+this library:
+
+- Non-standard variations on syntax, like `-long` options. This is non-standard
+  and should be avoided, so that is enforced by this library.
+- Completion of partial options, such as Python's `argparse` supplies for
+  incomplete arguments. It's better not to guess. Most third party command line
+  parsers for python actually reimplement command line parsing rather than using
+  argparse because of this perceived design flaw (recent versions do have an
+  option to disable it).
+- Autocomplete: This might eventually be added to both Plumbum and CLI11, but it
+  is not supported yet.
+- Wide strings / unicode: Since this uses the standard library only, it might be
+  hard to properly implement, but I would be open to suggestions in how to do
+  this.
  
 ## Install
  
 To use, there are several methods:
  
-- All-in-one local header: Copy `CLI11.hpp` from the [most recent release][github releases] into your include directory, and you are set. This is combined from the source files for every release. This includes the entire command parser library, but does not include separate utilities (like `Timer`, `AutoTimer`). The utilities are completely self contained and can be copied separately.
-- All-in-one global header: Like above, but copying the file to a shared folder location like `/opt/CLI11`. Then, the C++ include path has to be extended to point at this folder. With CMake, use `include_directories(/opt/CLI11)`
-- Local headers and target: Use `CLI/*.hpp` files. You could check out the repository as a git submodule, for example. With CMake, you can use `add_subdirectory` and the `CLI11::CLI11` interface target when linking. If not using a submodule, you must ensure that the copied files are located inside the same tree directory than your current project, to prevent an error with CMake and `add_subdirectory`.
-- Global headers: Use `CLI/*.hpp` files stored in a shared folder. You could check out the git repository to a system-wide folder, for example `/opt/`. With CMake, you could add to the include path via:
+- All-in-one local header: Copy `CLI11.hpp` from the [most recent
+  release][github releases] into your include directory, and you are set. This
+  is combined from the source files for every release. This includes the entire
+  command parser library, but does not include separate utilities (like `Timer`,
+  `AutoTimer`). The utilities are completely self contained and can be copied
+  separately.
+- All-in-one global header: Like above, but copying the file to a shared folder
+  location like `/opt/CLI11`. Then, the C++ include path has to be extended to
+  point at this folder. With CMake, use `include_directories(/opt/CLI11)`
+- Local headers and target: Use `CLI/*.hpp` files. You could check out the
+  repository as a git submodule, for example. With CMake, you can use
+  `add_subdirectory` and the `CLI11::CLI11` interface target when linking. If
+  not using a submodule, you must ensure that the copied files are located
+  inside the same tree directory than your current project, to prevent an error
+  with CMake and `add_subdirectory`.
+- Global headers: Use `CLI/*.hpp` files stored in a shared folder. You could
+  check out the git repository to a system-wide folder, for example `/opt/`.
+  With CMake, you could add to the include path via:
  
 ```bash
 if(NOT DEFINED CLI11_DIR)
@@ -150,7 +198,8 @@ endif()
 include_directories(${CLI11_DIR}/include)
 ```
  
-And then in the source code (adding several headers might be needed to prevent linker errors):
+And then in the source code (adding several headers might be needed to prevent
+linker errors):
  
 ```cpp
 #include "CLI/App.hpp"
@@ -158,10 +207,19 @@ And then in the source code (adding several headers might be needed to prevent l
 #include "CLI/Config.hpp"
 ```
  
-- Global headers and target: configuring and installing the project is required for linking CLI11 to your project in the same way as you would do with any other external library. With CMake, this step allows using `find_package(CLI11 CONFIG REQUIRED)` and then using the `CLI11::CLI11` target when linking. If `CMAKE_INSTALL_PREFIX` was changed during install to a specific folder like `/opt/CLI11`, then you have to pass `-DCLI11_DIR=/opt/CLI11` when building your current project. You can also use [Conan.io][conan-link] or [Hunter][].
-  (These are just conveniences to allow you to use your favorite method of managing packages; it's just header only so including the correct path and
-  using C++11 is all you really need.)
-- Via FetchContent in CMake 3.14+ (or 3.11+ with more work): you can add this with fetch-content, then use the `CLI11::CLI11` target as above, and CMake will download the project in the configure stage:
+- Global headers and target: configuring and installing the project is required
+  for linking CLI11 to your project in the same way as you would do with any
+  other external library. With CMake, this step allows using
+  `find_package(CLI11 CONFIG REQUIRED)` and then using the `CLI11::CLI11` target
+  when linking. If `CMAKE_INSTALL_PREFIX` was changed during install to a
+  specific folder like `/opt/CLI11`, then you have to pass
+  `-DCLI11_DIR=/opt/CLI11` when building your current project. You can also use
+  [Conan.io][conan-link] or [Hunter][]. (These are just conveniences to allow
+  you to use your favorite method of managing packages; it's just header only so
+  including the correct path and using C++11 is all you really need.)
+- Via FetchContent in CMake 3.14+ (or 3.11+ with more work): you can add this
+  with fetch-content, then use the `CLI11::CLI11` target as above, and CMake
+  will download the project in the configure stage:
  
 ```cmake
 include(FetchContent)
@@ -174,7 +232,11 @@ FetchContent_Declare(
 FetchContent_MakeAvailable(cli11)
 ```
  
-It is highly recommended that you use the git hash for `GIT_TAG` instead of a tag or branch, as that will both be more secure, as well as faster to reconfigure - CMake will not have to reach out to the internet to see if the tag moved. You can also download just the single header file from the releases using `file(DOWNLOAD`.
+It is highly recommended that you use the git hash for `GIT_TAG` instead of a
+tag or branch, as that will both be more secure, as well as faster to
+reconfigure - CMake will not have to reach out to the internet to see if the tag
+moved. You can also download just the single header file from the releases using
+`file(DOWNLOAD`.
  
 To build the tests, checkout the repository and use CMake:
  
@@ -186,15 +248,24 @@ CTEST_OUTPUT_ON_FAILURE=1 cmake --build build -t test
  
 <details><summary>Note: Special instructions for GCC 8</summary><p>
  
-If you are using GCC 8 and using it in C++17 mode with CLI11. CLI11 makes use of the `<filesystem>` header if available, but specifically for this compiler, the `filesystem` library is separate from the standard library and needs to be linked separately. So it is available but CLI11 doesn't use it by default.
+If you are using GCC 8 and using it in C++17 mode with CLI11. CLI11 makes use of
+the `<filesystem>` header if available, but specifically for this compiler, the
+`filesystem` library is separate from the standard library and needs to be
+linked separately. So it is available but CLI11 doesn't use it by default.
  
-Specifically `libstdc++fs` needs to be added to the linking list and `CLI11_HAS_FILESYSTEM=1` has to be defined. Then the filesystem variant of the Validators could be used on GCC 8. GCC 9+ does not have this issue so the `<filesystem>` is used by default.
+Specifically `libstdc++fs` needs to be added to the linking list and
+`CLI11_HAS_FILESYSTEM=1` has to be defined. Then the filesystem variant of the
+Validators could be used on GCC 8. GCC 9+ does not have this issue so the
+`<filesystem>` is used by default.
  
 There may also be other cases where a specific library needs to be linked.
  
-Defining `CLI11_HAS_FILESYSTEM=0` which will remove the usage and hence any linking issue.
+Defining `CLI11_HAS_FILESYSTEM=0` which will remove the usage and hence any
+linking issue.
  
-In some cases certain clang compilations may require linking against `libc++fs`. These situations have not been encountered so the specific situations requiring them are unknown yet.
+In some cases certain clang compilations may require linking against `libc++fs`.
+These situations have not been encountered so the specific situations requiring
+them are unknown yet.
  
 </p></details>
 </br>
@@ -203,7 +274,8 @@ In some cases certain clang compilations may require linking against `libc++fs`.
  
 ### Adding options
  
-To set up, add options, and run, your main function will look something like this:
+To set up, add options, and run, your main function will look something like
+this:
  
 ```cpp
 int main(int argc, char** argv) {
@@ -227,16 +299,26 @@ try {
 }
 ```
  
-The try/catch block ensures that `-h,--help` or a parse error will exit with the correct return code (selected from `CLI::ExitCodes`). (The return here should be inside `main`). You should not assume that the option values have been set inside the catch block; for example, help flags intentionally short-circuit all other processing for speed and to ensure required options and the like do not interfere.
+The try/catch block ensures that `-h,--help` or a parse error will exit with the
+correct return code (selected from `CLI::ExitCodes`). (The return here should be
+inside `main`). You should not assume that the option values have been set
+inside the catch block; for example, help flags intentionally short-circuit all
+other processing for speed and to ensure required options and the like do not
+interfere.
  
 </p></details>
 </br>
  
-The initialization is just one line, adding options is just two each. The parse macro is just one line (or 5 for the contents of the macro). After the app runs, the filename will be set to the correct value if it was passed, otherwise it will be set to the default. You can check to see if this was passed on the command line with `app.count("--file")`.
+The initialization is just one line, adding options is just two each. The parse
+macro is just one line (or 5 for the contents of the macro). After the app runs,
+the filename will be set to the correct value if it was passed, otherwise it
+will be set to the default. You can check to see if this was passed on the
+command line with `app.count("--file")`.
  
 #### Option types
  
-While all options internally are the same type, there are several ways to add an option depending on what you need. The supported values are:
+While all options internally are the same type, there are several ways to add an
+option depending on what you need. The supported values are:
  
 ```cpp
 // Add options
@@ -277,18 +359,32 @@ App* subcom = app.add_subcommand(name, description);
 Option_group *app.add_option_group(name,description);
 ```
  
-An option name may start with any character except ('-', ' ', '\n', and '!'). For long options, after the first character all characters are allowed except ('=',':','{',' ', '\n'). For the `add_flag*` functions '{' and '!' have special meaning which is why they are not allowed. Names are given as a comma separated string, with the dash or dashes. An option or flag can have as many names as you want, and afterward, using `count`, you can use any of the names, with dashes as needed, to count the options. One of the names is allowed to be given without proceeding dash(es); if present the option is a positional option, and that name will be used on the help line for its positional form.
-
-The `add_option_function<type>(...` function will typically require the template parameter be given unless a `std::function` object with an exact match is passed. The type can be any type supported by the `add_option` function. The function should throw an error (`CLI::ConversionError` or `CLI::ValidationError` possibly) if the value is not valid.
-
-The two parameter template overload can be used in cases where you want to restrict the input such as
+An option name may start with any character except ('-', ' ', '\n', and '!').
+For long options, after the first character all characters are allowed except
+('=',':','{',' ', '\n'). For the `add_flag*` functions '{' and '!' have special
+meaning which is why they are not allowed. Names are given as a comma separated
+string, with the dash or dashes. An option or flag can have as many names as you
+want, and afterward, using `count`, you can use any of the names, with dashes as
+needed, to count the options. One of the names is allowed to be given without
+proceeding dash(es); if present the option is a positional option, and that name
+will be used on the help line for its positional form.
+
+The `add_option_function<type>(...` function will typically require the template
+parameter be given unless a `std::function` object with an exact match is
+passed. The type can be any type supported by the `add_option` function. The
+function should throw an error (`CLI::ConversionError` or `CLI::ValidationError`
+possibly) if the value is not valid.
+
+The two parameter template overload can be used in cases where you want to
+restrict the input such as
  
 ```cpp
 double val
 app.add_option<double,unsigned int>("-v",val);
 ```
  
-which would first verify the input is convertible to an `unsigned int` before assigning it. Or using some variant type
+which would first verify the input is convertible to an `unsigned int` before
+assigning it. Or using some variant type
  
 ```cpp
 using vtype=std::variant<int, double, std::string>;
@@ -298,9 +394,19 @@ app.add_option&lt;vtype,int&gt;(&quot;--vi&quot;,v1);
 app.add_option<vtype,double>("--vf",v1);
 ```
  
-otherwise the output would default to a string. The `add_option` can be used with any integral or floating point types, enumerations, or strings. Or any type that takes an int, double, or std\::string in an assignment operator or constructor. If an object can take multiple varieties of those, std::string takes precedence, then double then int. To better control which one is used or to use another type for the underlying conversions use the two parameter template to directly specify the conversion type.
+otherwise the output would default to a string. The `add_option` can be used
+with any integral or floating point types, enumerations, or strings. Or any type
+that takes an int, double, or std\::string in an assignment operator or
+constructor. If an object can take multiple varieties of those, std::string
+takes precedence, then double then int. To better control which one is used or
+to use another type for the underlying conversions use the two parameter
+template to directly specify the conversion type.
  
-Types such as (std or boost) `optional<int>`, `optional<double>`, and `optional<string>` and any other wrapper types are supported directly. For purposes of CLI11 wrapper types are those which `value_type` definition. See [CLI11 Advanced Topics/Custom Converters][] for information on how you can add your own converters for additional types.
+Types such as (std or boost) `optional<int>`, `optional<double>`, and
+`optional<string>` and any other wrapper types are supported directly. For
+purposes of CLI11 wrapper types are those which `value_type` definition. See
+[CLI11 Advanced Topics/Custom Converters][] for information on how you can add
+your own converters for additional types.
  
 Vector types can also be used in the two parameter template overload
  
@@ -309,79 +415,175 @@ std::vector&lt;double&gt; v1;
 app.add_option<std::vector<double>,int>("--vs",v1);
 ```
  
-would load a vector of doubles but ensure all values can be represented as integers.
+would load a vector of doubles but ensure all values can be represented as
+integers.
  
-Automatic direct capture of the default string is disabled when using the two parameter template. Use `set_default_str(...)` or `->default_function(std::string())` to set the default string or capture function directly for these cases.
+Automatic direct capture of the default string is disabled when using the two
+parameter template. Use `set_default_str(...)` or
+`->default_function(std::string())` to set the default string or capture
+function directly for these cases.
  
-Flag options specified through the `add_flag*` functions allow a syntax for the option names to default particular options to a false value or any other value if some flags are passed. For example:
+Flag options specified through the `add_flag*` functions allow a syntax for the
+option names to default particular options to a false value or any other value
+if some flags are passed. For example:
  
 ```cpp
 app.add_flag("--flag,!--no-flag",result,"help for flag");
 ```
  
-specifies that if `--flag` is passed on the command line result will be true or contain a value of 1. If `--no-flag` is
-passed `result` will contain false or -1 if `result` is a signed integer type, or 0 if it is an unsigned type. An
-alternative form of the syntax is more explicit: `"--flag,--no-flag{false}"`; this is equivalent to the previous
-example. This also works for short form options `"-f,!-n"` or `"-f,-n{false}"`. If `variable_to_bind_to` is anything but an integer value the
-default behavior is to take the last value given, while if `variable_to_bind_to` is an integer type the behavior will be to sum
-all the given arguments and return the result. This can be modified if needed by changing the `multi_option_policy` on each flag (this is not inherited).
-The default value can be any value. For example if you wished to define a numerical flag:
+specifies that if `--flag` is passed on the command line result will be true or
+contain a value of 1. If `--no-flag` is passed `result` will contain false or -1
+if `result` is a signed integer type, or 0 if it is an unsigned type. An
+alternative form of the syntax is more explicit: `"--flag,--no-flag{false}"`;
+this is equivalent to the previous example. This also works for short form
+options `"-f,!-n"` or `"-f,-n{false}"`. If `variable_to_bind_to` is anything but
+an integer value the default behavior is to take the last value given, while if
+`variable_to_bind_to` is an integer type the behavior will be to sum all the
+given arguments and return the result. This can be modified if needed by
+changing the `multi_option_policy` on each flag (this is not inherited). The
+default value can be any value. For example if you wished to define a numerical
+flag:
  
 ```cpp
 app.add_flag("-1{1},-2{2},-3{3}",result,"numerical flag")
 ```
  
-Using any of those flags on the command line will result in the specified number in the output. Similar things can be done for string values, and enumerations, as long as the default value can be converted to the given type.
+Using any of those flags on the command line will result in the specified number
+in the output. Similar things can be done for string values, and enumerations,
+as long as the default value can be converted to the given type.
  
-On a `C++14` compiler, you can pass a callback function directly to `.add_flag`, while in C++11 mode you'll need to use `.add_flag_function` if you want a callback function. The function will be given the number of times the flag was passed. You can throw a relevant `CLI::ParseError` to signal a failure.
+On a `C++14` compiler, you can pass a callback function directly to `.add_flag`,
+while in C++11 mode you'll need to use `.add_flag_function` if you want a
+callback function. The function will be given the number of times the flag was
+passed. You can throw a relevant `CLI::ParseError` to signal a failure.
  
 #### Example
  
-- `"one,-o,--one"`: Valid as long as not a flag, would create an option that can be specified positionally, or with `-o` or `--one`
+- `"one,-o,--one"`: Valid as long as not a flag, would create an option that can
+  be specified positionally, or with `-o` or `--one`
 - `"this"` Can only be passed positionally
 - `"-a,-b,-c"` No limit to the number of non-positional option names
  
-The add commands return a pointer to an internally stored `Option`.
-This option can be used directly to check for the count (`->count()`) after parsing to avoid a string based lookup.
+The add commands return a pointer to an internally stored `Option`. This option
+can be used directly to check for the count (`->count()`) after parsing to avoid
+a string based lookup.
  
 #### Option options
  
 Before parsing, you can set the following options:
  
-- `->required()`: The program will quit if this option is not present. This is `mandatory` in Plumbum, but required options seems to be a more standard term. For compatibility, `->mandatory()` also works.
-- `->expected(N)`: Take `N` values instead of as many as possible, only for vector args. If negative, require at least `-N`; end with `--` or another recognized option or subcommand.
-- `->expected(MIN,MAX)`: Set a range of expected values to accompany an option. `expected(0,1)` is the equivalent of making a flag.
-- `->type_name(typename)`: Set the name of an Option's type (`type_name_fn` allows a function instead)
-- `->type_size(N)`: Set the intrinsic size of an option value. The parser will require multiples of this number if negative. Most of the time this is detected automatically though can be modified for specific use cases.
+- `->required()`: The program will quit if this option is not present. This is
+  `mandatory` in Plumbum, but required options seems to be a more standard term.
+  For compatibility, `->mandatory()` also works.
+- `->expected(N)`: Take `N` values instead of as many as possible, only for
+  vector args. If negative, require at least `-N`; end with `--` or another
+  recognized option or subcommand.
+- `->expected(MIN,MAX)`: Set a range of expected values to accompany an option.
+  `expected(0,1)` is the equivalent of making a flag.
+- `->type_name(typename)`: Set the name of an Option's type (`type_name_fn`
+  allows a function instead)
+- `->type_size(N)`: Set the intrinsic size of an option value. The parser will
+  require multiples of this number if negative. Most of the time this is
+  detected automatically though can be modified for specific use cases.
 - `->type_size(MIN,MAX)`: Set the intrinsic size of an option to a range.
-- `->needs(opt)`: This option requires another option to also be present, opt is an `Option` pointer. Options can be removed from the `needs` with `remove_needs(opt)`. The option can also be specified with a string containing the name of the option
-- `->excludes(opt)`: This option cannot be given with `opt` present, opt is an `Option` pointer. Can also be given as a string containing the name of the option. Options can be removed from the excludes list with `->remove_excludes(opt)`
-- `->envname(name)`: Gets the value from the environment if present and not passed on the command line.
-- `->group(name)`: The help group to put the option in. No effect for positional options. Defaults to `"Options"`. `""` will not show up in the help print (hidden).
-- `->ignore_case()`: Ignore the case on the command line (also works on subcommands, does not affect arguments).
-- `->ignore_underscore()`: Ignore any underscores in the options names (also works on subcommands, does not affect arguments). For example "option_one" will match with "optionone". This does not apply to short form options since they only have one character
-- `->disable_flag_override()`: From the command line long form flag options can be assigned a value on the command line using the `=` notation `--flag=value`. If this behavior is not desired, the `disable_flag_override()` disables it and will generate an exception if it is done on the command line. The `=` does not work with short form flag options.
-- `->allow_extra_args(true/false)`: If set to true the option will take an unlimited number of arguments like a vector, if false it will limit the number of arguments to the size of the type used in the option. Default value depends on the nature of the type use, containers default to true, others default to false.
-- `->delimiter(char)`: Allows specification of a custom delimiter for separating single arguments into vector arguments, for example specifying `->delimiter(',')` on an option would result in `--opt=1,2,3` producing 3 elements of a vector and the equivalent of --opt 1 2 3 assuming opt is a vector value.
+- `->needs(opt)`: This option requires another option to also be present, opt is
+  an `Option` pointer. Options can be removed from the `needs` with
+  `remove_needs(opt)`. The option can also be specified with a string containing
+  the name of the option
+- `->excludes(opt)`: This option cannot be given with `opt` present, opt is an
+  `Option` pointer. Can also be given as a string containing the name of the
+  option. Options can be removed from the excludes list with
+  `->remove_excludes(opt)`
+- `->envname(name)`: Gets the value from the environment if present and not
+  passed on the command line.
+- `->group(name)`: The help group to put the option in. No effect for positional
+  options. Defaults to `"Options"`. `""` will not show up in the help print
+  (hidden).
+- `->ignore_case()`: Ignore the case on the command line (also works on
+  subcommands, does not affect arguments).
+- `->ignore_underscore()`: Ignore any underscores in the options names (also
+  works on subcommands, does not affect arguments). For example "option_one"
+  will match with "optionone". This does not apply to short form options since
+  they only have one character
+- `->disable_flag_override()`: From the command line long form flag options can
+  be assigned a value on the command line using the `=` notation `--flag=value`.
+  If this behavior is not desired, the `disable_flag_override()` disables it and
+  will generate an exception if it is done on the command line. The `=` does not
+  work with short form flag options.
+- `->allow_extra_args(true/false)`: If set to true the option will take an
+  unlimited number of arguments like a vector, if false it will limit the number
+  of arguments to the size of the type used in the option. Default value depends
+  on the nature of the type use, containers default to true, others default to
+  false.
+- `->delimiter(char)`: Allows specification of a custom delimiter for separating
+  single arguments into vector arguments, for example specifying
+  `->delimiter(',')` on an option would result in `--opt=1,2,3` producing 3
+  elements of a vector and the equivalent of --opt 1 2 3 assuming opt is a
+  vector value.
 - `->description(str)`: Set/change the description.
-- `->multi_option_policy(CLI::MultiOptionPolicy::Throw)`: Set the multi-option policy. Shortcuts available: `->take_last()`, `->take_first()`,`->take_all()`, and `->join()`. This will only affect options expecting 1 argument or bool flags (which do not inherit their default but always start with a specific policy). `->join(delim)` can also be used to join with a specific delimiter. This equivalent to calling `->delimiter(delim)` and `->join()`. Valid values are `CLI::MultiOptionPolicy::Throw`, `CLI::MultiOptionPolicy::Throw`, `CLI::MultiOptionPolicy::TakeLast`, `CLI::MultiOptionPolicy::TakeFirst`, `CLI::MultiOptionPolicy::Join`, `CLI::MultiOptionPolicy::TakeAll`, and `CLI::MultiOptionPolicy::Sum` 🚧.
-- `->check(std::string(const std::string &), validator_name="",validator_description="")`: Define a check function. The function should return a non empty string with the error message if the check fails
-- `->check(Validator)`: Use a Validator object to do the check see [Validators](#validators) for a description of available Validators and how to create new ones.
-- `->transform(std::string(std::string &), validator_name="",validator_description=")`: Converts the input string into the output string, in-place in the parsed options.
-- `->transform(Validator)`: Uses a Validator object to do the transformation see [Validators](#validators) for a description of available Validators and how to create new ones.
-- `->each(void(const std::string &)>`: Run this function on each value received, as it is received. It should throw a `ValidationError` if an error is encountered.
-- `->configurable(false)`: Disable this option from being in a configuration file.
-- `->capture_default_str()`: Store the current value attached and display it in the help string.
-- `->default_function(std::string())`: Advanced: Change the function that `capture_default_str()` uses.
-- `->always_capture_default()`: Always run `capture_default_str()` when creating new options. Only useful on an App's `option_defaults`.
-- `->default_str(string)`: Set the default string directly (NO VALIDATION OR CALLBACKS). This string will also be used as a default value if no arguments are passed and the value is requested.
-- `->default_val(value)`: Generate the default string from a value and validate that the value is also valid. For options that assign directly to a value type the value in that type is also updated. Value must be convertible to a string(one of known types or have a stream operator). The callback may be triggered if the `run_callback_for_default` is set.
-- `->run_callback_for_default()`: This will force the option callback to be executed or the variable set when the `default_val` is set.
-- `->option_text(string)`: Sets the text between the option name and description.
-- `->force_callback()`: Causes the option callback or value set to be triggered even if the option was not present in parsing.
-- `->trigger_on_parse()`: If set, causes the callback and all associated validation checks for the option to be executed when the option value is parsed vs. at the end of all parsing. This could cause the callback to be executed multiple times. Also works with positional options 🆕.
-
-These options return the `Option` pointer, so you can chain them together, and even skip storing the pointer entirely. The `each` function takes any function that has the signature `void(const std::string&)`; it should throw a `ValidationError` when validation fails. The help message will have the name of the parent option prepended. Since `each`, `check` and `transform` use the same underlying mechanism, you can chain as many as you want, and they will be executed in order. Operations added through `transform` are executed first in reverse order of addition, and `check` and `each` are run following the transform functions in order of addition. If you just want to see the unconverted values, use `.results()` to get the `std::vector<std::string>` of results.
+- `->multi_option_policy(CLI::MultiOptionPolicy::Throw)`: Set the multi-option
+  policy. Shortcuts available: `->take_last()`, `->take_first()`,`->take_all()`,
+  and `->join()`. This will only affect options expecting 1 argument or bool
+  flags (which do not inherit their default but always start with a specific
+  policy). `->join(delim)` can also be used to join with a specific delimiter.
+  This equivalent to calling `->delimiter(delim)` and `->join()`. Valid values
+  are `CLI::MultiOptionPolicy::Throw`, `CLI::MultiOptionPolicy::Throw`,
+  `CLI::MultiOptionPolicy::TakeLast`, `CLI::MultiOptionPolicy::TakeFirst`,
+  `CLI::MultiOptionPolicy::Join`, `CLI::MultiOptionPolicy::TakeAll`, and
+  `CLI::MultiOptionPolicy::Sum` 🚧.
+- `->check(std::string(const std::string &), validator_name="",validator_description="")`:
+  Define a check function. The function should return a non empty string with
+  the error message if the check fails
+- `->check(Validator)`: Use a Validator object to do the check see
+  [Validators](#validators) for a description of available Validators and how to
+  create new ones.
+- `->transform(std::string(std::string &), validator_name="",validator_description=")`:
+  Converts the input string into the output string, in-place in the parsed
+  options.
+- `->transform(Validator)`: Uses a Validator object to do the transformation see
+  [Validators](#validators) for a description of available Validators and how to
+  create new ones.
+- `->each(void(const std::string &)>`: Run this function on each value received,
+  as it is received. It should throw a `ValidationError` if an error is
+  encountered.
+- `->configurable(false)`: Disable this option from being in a configuration
+  file.
+- `->capture_default_str()`: Store the current value attached and display it in
+  the help string.
+- `->default_function(std::string())`: Advanced: Change the function that
+  `capture_default_str()` uses.
+- `->always_capture_default()`: Always run `capture_default_str()` when creating
+  new options. Only useful on an App's `option_defaults`.
+- `->default_str(string)`: Set the default string directly (NO VALIDATION OR
+  CALLBACKS). This string will also be used as a default value if no arguments
+  are passed and the value is requested.
+- `->default_val(value)`: Generate the default string from a value and validate
+  that the value is also valid. For options that assign directly to a value type
+  the value in that type is also updated. Value must be convertible to a
+  string(one of known types or have a stream operator). The callback may be
+  triggered if the `run_callback_for_default` is set.
+- `->run_callback_for_default()`: This will force the option callback to be
+  executed or the variable set when the `default_val` is set.
+- `->option_text(string)`: Sets the text between the option name and
+  description.
+- `->force_callback()`: Causes the option callback or value set to be triggered
+  even if the option was not present in parsing.
+- `->trigger_on_parse()`: If set, causes the callback and all associated
+  validation checks for the option to be executed when the option value is
+  parsed vs. at the end of all parsing. This could cause the callback to be
+  executed multiple times. Also works with positional options 🆕.
+
+These options return the `Option` pointer, so you can chain them together, and
+even skip storing the pointer entirely. The `each` function takes any function
+that has the signature `void(const std::string&)`; it should throw a
+`ValidationError` when validation fails. The help message will have the name of
+the parent option prepended. Since `each`, `check` and `transform` use the same
+underlying mechanism, you can chain as many as you want, and they will be
+executed in order. Operations added through `transform` are executed first in
+reverse order of addition, and `check` and `each` are run following the
+transform functions in order of addition. If you just want to see the
+unconverted values, use `.results()` to get the `std::vector<std::string>` of
+results.
  
 On the command line, options can be given as:
  
@@ -395,7 +597,8 @@ On the command line, options can be given as:
 - `--file filename` (space)
 - `--file=filename` (equals)
  
-If `allow_windows_style_options()` is specified in the application or subcommand options can also be given as:
+If `allow_windows_style_options()` is specified in the application or subcommand
+options can also be given as:
  
 - `/a` (flag)
 - `/f filename` (option)
@@ -403,43 +606,78 @@ If `allow_windows_style_options()` is specified in the application or subcommand
 - `/file filename` (space)
 - `/file:filename` (colon)
 - `/long_flag:false` (long flag with : to override the default value)
-  - Windows style options do not allow combining short options or values not separated from the short option like with `-` options
-
-Long flag options may be given with an `=<value>` to allow specifying a false value, or some other value to the flag. See [config files](#configuration-file) for details on the values supported. NOTE: only the `=` or `:` for windows-style options may be used for this, using a space will result in the argument being interpreted as a positional argument. This syntax can override the default values, and can be disabled by using `disable_flag_override()`.
-
-Extra positional arguments will cause the program to exit, so at least one positional option with a vector is recommended if you want to allow extraneous arguments.
-If you set `.allow_extras()` on the main `App`, you will not get an error. You can access the missing options using `remaining` (if you have subcommands, `app.remaining(true)` will get all remaining options, subcommands included).
-If the remaining arguments are to processed by another `App` then the function `remaining_for_passthrough()` can be used to get the remaining arguments in reverse order such that `app.parse(vector)` works directly and could even be used inside a subcommand callback.
-
-You can access a vector of pointers to the parsed options in the original order using `parse_order()`.
-If `--` is present in the command line that does not end an unlimited option, then
-everything after that is positional only.
+  - Windows style options do not allow combining short options or values not
+    separated from the short option like with `-` options
+
+Long flag options may be given with an `=<value>` to allow specifying a false
+value, or some other value to the flag. See [config files](#configuration-file)
+for details on the values supported. NOTE: only the `=` or `:` for windows-style
+options may be used for this, using a space will result in the argument being
+interpreted as a positional argument. This syntax can override the default
+values, and can be disabled by using `disable_flag_override()`.
+
+Extra positional arguments will cause the program to exit, so at least one
+positional option with a vector is recommended if you want to allow extraneous
+arguments. If you set `.allow_extras()` on the main `App`, you will not get an
+error. You can access the missing options using `remaining` (if you have
+subcommands, `app.remaining(true)` will get all remaining options, subcommands
+included). If the remaining arguments are to processed by another `App` then the
+function `remaining_for_passthrough()` can be used to get the remaining
+arguments in reverse order such that `app.parse(vector)` works directly and
+could even be used inside a subcommand callback.
+
+You can access a vector of pointers to the parsed options in the original order
+using `parse_order()`. If `--` is present in the command line that does not end
+an unlimited option, then everything after that is positional only.
  
 #### Validators
  
-Validators are structures to check or modify inputs, they can be used to verify that an input meets certain criteria or transform it into another value. They are added through the `check` or `transform` functions. The differences between the two function are that checks do not modify the input whereas transforms can and are executed before any Validators added through `check`.
+Validators are structures to check or modify inputs, they can be used to verify
+that an input meets certain criteria or transform it into another value. They
+are added through the `check` or `transform` functions. The differences between
+the two function are that checks do not modify the input whereas transforms can
+and are executed before any Validators added through `check`.
  
 CLI11 has several Validators built-in that perform some common checks
  
-- `CLI::IsMember(...)`: Require an option be a member of a given set. See [Transforming Validators](#transforming-validators) for more details.
-- `CLI::Transformer(...)`: Modify the input using a map. See [Transforming Validators](#transforming-validators) for more details.
-- `CLI::CheckedTransformer(...)`: Modify the input using a map, and require that the input is either in the set or already one of the outputs of the set. See [Transforming Validators](#transforming-validators) for more details.
-- `CLI::AsNumberWithUnit(...)`: Modify the `<NUMBER> <UNIT>` pair by matching the unit and multiplying the number by the corresponding factor. It can be used as a base for transformers, that accept things like size values (`1 KB`) or durations (`0.33 ms`).
-- `CLI::AsSizeValue(...)`: Convert inputs like `100b`, `42 KB`, `101 Mb`, `11 Mib` to absolute values. `KB` can be configured to be interpreted as 10^3 or 2^10.
+- `CLI::IsMember(...)`: Require an option be a member of a given set. See
+  [Transforming Validators](#transforming-validators) for more details.
+- `CLI::Transformer(...)`: Modify the input using a map. See
+  [Transforming Validators](#transforming-validators) for more details.
+- `CLI::CheckedTransformer(...)`: Modify the input using a map, and require that
+  the input is either in the set or already one of the outputs of the set. See
+  [Transforming Validators](#transforming-validators) for more details.
+- `CLI::AsNumberWithUnit(...)`: Modify the `<NUMBER> <UNIT>` pair by matching
+  the unit and multiplying the number by the corresponding factor. It can be
+  used as a base for transformers, that accept things like size values (`1 KB`)
+  or durations (`0.33 ms`).
+- `CLI::AsSizeValue(...)`: Convert inputs like `100b`, `42 KB`, `101 Mb`,
+  `11 Mib` to absolute values. `KB` can be configured to be interpreted as 10^3
+  or 2^10.
 - `CLI::ExistingFile`: Requires that the file exists if given.
 - `CLI::ExistingDirectory`: Requires that the directory exists.
 - `CLI::ExistingPath`: Requires that the path (file or directory) exists.
 - `CLI::NonexistentPath`: Requires that the path does not exist.
-- `CLI::FileOnDefaultPath`: 🆕 Best used as a transform, Will check that a file exists either directly or in a default path and update the path appropriately. See [Transforming Validators](#transforming-validators) for more details
-- `CLI::Range(min,max)`: Requires that the option be between min and max (make sure to use floating point if needed). Min defaults to 0.
-- `CLI::Bounded(min,max)`: Modify the input such that it is always between min and max (make sure to use floating point if needed). Min defaults to 0. Will produce an error if conversion is not possible.
+- `CLI::FileOnDefaultPath`: 🆕 Best used as a transform, Will check that a file
+  exists either directly or in a default path and update the path appropriately.
+  See [Transforming Validators](#transforming-validators) for more details
+- `CLI::Range(min,max)`: Requires that the option be between min and max (make
+  sure to use floating point if needed). Min defaults to 0.
+- `CLI::Bounded(min,max)`: Modify the input such that it is always between min
+  and max (make sure to use floating point if needed). Min defaults to 0. Will
+  produce an error if conversion is not possible.
 - `CLI::PositiveNumber`: Requires the number be greater than 0
 - `CLI::NonNegativeNumber`: Requires the number be greater or equal to 0
 - `CLI::Number`: Requires the input be a number.
-- `CLI::ValidIPV4`: Requires that the option be a valid IPv4 string e.g. `'255.255.255.255'`, `'10.1.1.7'`.
-- `CLI::TypeValidator<TYPE>`:Requires that the option be convertible to the specified type e.g. `CLI::TypeValidator<unsigned int>()` would require that the input be convertible to an `unsigned int` regardless of the end conversion.
+- `CLI::ValidIPV4`: Requires that the option be a valid IPv4 string e.g.
+  `'255.255.255.255'`, `'10.1.1.7'`.
+- `CLI::TypeValidator<TYPE>`:Requires that the option be convertible to the
+  specified type e.g. `CLI::TypeValidator<unsigned int>()` would require that
+  the input be convertible to an `unsigned int` regardless of the end
+  conversion.
  
-These Validators can be used by simply passing the name into the `check` or `transform` methods on an option
+These Validators can be used by simply passing the name into the `check` or
+`transform` methods on an option
  
 ```cpp
 ->check(CLI::ExistingFile);
@@ -462,53 +700,116 @@ will produce a check for a number less than or equal to 0.
  
 ##### Transforming Validators
  
-There are a few built in Validators that let you transform values if used with the `transform` function. If they also do some checks then they can be used `check` but some may do nothing in that case.
-
-- `CLI::Bounded(min,max)` will bound values between min and max and values outside of that range are limited to min or max, it will fail if the value cannot be converted and produce a `ValidationError`
-- The `IsMember` Validator lets you specify a set of predefined options. You can pass any container or copyable pointer (including `std::shared_ptr`) to a container to this Validator; the container just needs to be iterable and have a `::value_type`. The key type should be convertible from a string, You can use an initializer list directly if you like. If you need to modify the set later, the pointer form lets you do that; the type message and check will correctly refer to the current version of the set. The container passed in can be a set, vector, or a map like structure. If used in the `transform` method the output value will be the matching key as it could be modified by filters.
-
-After specifying a set of options, you can also specify "filter" functions of the form `T(T)`, where `T` is the type of the values. The most common choices probably will be `CLI::ignore_case` an `CLI::ignore_underscore`, and `CLI::ignore_space`. These all work on strings but it is possible to define functions that work on other types. Here are some examples of `IsMember`:
+There are a few built in Validators that let you transform values if used with
+the `transform` function. If they also do some checks then they can be used
+`check` but some may do nothing in that case.
+
+- `CLI::Bounded(min,max)` will bound values between min and max and values
+  outside of that range are limited to min or max, it will fail if the value
+  cannot be converted and produce a `ValidationError`
+- The `IsMember` Validator lets you specify a set of predefined options. You can
+  pass any container or copyable pointer (including `std::shared_ptr`) to a
+  container to this Validator; the container just needs to be iterable and have
+  a `::value_type`. The key type should be convertible from a string, You can
+  use an initializer list directly if you like. If you need to modify the set
+  later, the pointer form lets you do that; the type message and check will
+  correctly refer to the current version of the set. The container passed in can
+  be a set, vector, or a map like structure. If used in the `transform` method
+  the output value will be the matching key as it could be modified by filters.
+
+After specifying a set of options, you can also specify "filter" functions of
+the form `T(T)`, where `T` is the type of the values. The most common choices
+probably will be `CLI::ignore_case` an `CLI::ignore_underscore`, and
+`CLI::ignore_space`. These all work on strings but it is possible to define
+functions that work on other types. Here are some examples of `IsMember`:
  
 - `CLI::IsMember({"choice1", "choice2"})`: Select from exact match to choices.
-- `CLI::IsMember({"choice1", "choice2"}, CLI::ignore_case, CLI::ignore_underscore)`: Match things like `Choice_1`, too.
-- `CLI::IsMember(std::set<int>({2,3,4}))`: Most containers and types work; you just need `std::begin`, `std::end`, and `::value_type`.
-- `CLI::IsMember(std::map<std::string, TYPE>({{"one", 1}, {"two", 2}}))`: You can use maps; in `->transform()` these replace the matched value with the matched key. The value member of the map is not used in `IsMember`, so it can be any type.
-- `auto p = std::make_shared<std::vector<std::string>>(std::initializer_list<std::string>("one", "two")); CLI::IsMember(p)`: You can modify `p` later.
-- The `Transformer` and `CheckedTransformer` Validators transform one value into another. Any container or copyable pointer (including `std::shared_ptr`) to a container that generates pairs of values can be passed to these `Validator's`; the container just needs to be iterable and have a `::value_type` that consists of pairs. The key type should be convertible from a string, and the value type should be convertible to a string You can use an initializer list directly if you like. If you need to modify the map later, the pointer form lets you do that; the description message will correctly refer to the current version of the map. `Transformer` does not do any checking so values not in the map are ignored. `CheckedTransformer` takes an extra step of verifying that the value is either one of the map key values, in which case it is transformed, or one of the expected output values, and if not will generate a `ValidationError`. A Transformer placed using `check` will not do anything.
-
-After specifying a map of options, you can also specify "filter" just like in `CLI::IsMember`.
-Here are some examples (`Transformer` and `CheckedTransformer` are interchangeable in the examples)
-of `Transformer`:
-
-- `CLI::Transformer({{"key1", "map1"},{"key2","map2"}})`: Select from key values and produce map values.
-- `CLI::Transformer(std::map<std::string,int>({"two",2},{"three",3},{"four",4}}))`: most maplike containers work, the `::value_type` needs to produce a pair of some kind.
-- `CLI::CheckedTransformer(std::map<std::string, int>({{"one", 1}, {"two", 2}}))`: You can use maps; in `->transform()` these replace the matched key with the value. `CheckedTransformer` also requires that the value either match one of the keys or match one of known outputs.
-- `auto p = std::make_shared<CLI::TransformPairs<std::string>>(std::initializer_list<std::pair<std::string,std::string>>({"key1", "map1"},{"key2","map2"})); CLI::Transformer(p)`: You can modify `p` later. `TransformPairs<T>` is an alias for `std::vector<std::pair<<std::string,T>>`
-
-NOTES: If the container used in `IsMember`, `Transformer`, or `CheckedTransformer` has a `find` function like `std::unordered_map` or `std::map` then that function is used to do the searching. If it does not have a `find` function a linear search is performed. If there are filters present, the fast search is performed first, and if that fails a linear search with the filters on the key values is performed.
-
-- `CLI::FileOnDefaultPath(default_path)`: 🆕 can be used to check for files in a default path. If used as a transform it will first check that a file exists, if it does nothing further is done, if it does not it tries to add a default Path to the file and search there again. If the file does not exist an error is returned normally but this can be disabled using CLI::FileOnDefaultPath(default_path, false). This allows multiple paths to be chained using multiple transform calls.
+- `CLI::IsMember({"choice1", "choice2"}, CLI::ignore_case, CLI::ignore_underscore)`:
+  Match things like `Choice_1`, too.
+- `CLI::IsMember(std::set<int>({2,3,4}))`: Most containers and types work; you
+  just need `std::begin`, `std::end`, and `::value_type`.
+- `CLI::IsMember(std::map<std::string, TYPE>({{"one", 1}, {"two", 2}}))`: You
+  can use maps; in `->transform()` these replace the matched value with the
+  matched key. The value member of the map is not used in `IsMember`, so it can
+  be any type.
+- `auto p = std::make_shared<std::vector<std::string>>(std::initializer_list<std::string>("one", "two")); CLI::IsMember(p)`:
+  You can modify `p` later.
+- The `Transformer` and `CheckedTransformer` Validators transform one value into
+  another. Any container or copyable pointer (including `std::shared_ptr`) to a
+  container that generates pairs of values can be passed to these `Validator's`;
+  the container just needs to be iterable and have a `::value_type` that
+  consists of pairs. The key type should be convertible from a string, and the
+  value type should be convertible to a string You can use an initializer list
+  directly if you like. If you need to modify the map later, the pointer form
+  lets you do that; the description message will correctly refer to the current
+  version of the map. `Transformer` does not do any checking so values not in
+  the map are ignored. `CheckedTransformer` takes an extra step of verifying
+  that the value is either one of the map key values, in which case it is
+  transformed, or one of the expected output values, and if not will generate a
+  `ValidationError`. A Transformer placed using `check` will not do anything.
+
+After specifying a map of options, you can also specify "filter" just like in
+`CLI::IsMember`. Here are some examples (`Transformer` and `CheckedTransformer`
+are interchangeable in the examples) of `Transformer`:
+
+- `CLI::Transformer({{"key1", "map1"},{"key2","map2"}})`: Select from key values
+  and produce map values.
+- `CLI::Transformer(std::map<std::string,int>({"two",2},{"three",3},{"four",4}}))`:
+  most maplike containers work, the `::value_type` needs to produce a pair of
+  some kind.
+- `CLI::CheckedTransformer(std::map<std::string, int>({{"one", 1}, {"two", 2}}))`:
+  You can use maps; in `->transform()` these replace the matched key with the
+  value. `CheckedTransformer` also requires that the value either match one of
+  the keys or match one of known outputs.
+- `auto p = std::make_shared<CLI::TransformPairs<std::string>>(std::initializer_list<std::pair<std::string,std::string>>({"key1", "map1"},{"key2","map2"})); CLI::Transformer(p)`:
+  You can modify `p` later. `TransformPairs<T>` is an alias for
+  `std::vector<std::pair<<std::string,T>>`
+
+NOTES: If the container used in `IsMember`, `Transformer`, or
+`CheckedTransformer` has a `find` function like `std::unordered_map` or
+`std::map` then that function is used to do the searching. If it does not have a
+`find` function a linear search is performed. If there are filters present, the
+fast search is performed first, and if that fails a linear search with the
+filters on the key values is performed.
+
+- `CLI::FileOnDefaultPath(default_path)`: 🆕 can be used to check for files in a
+  default path. If used as a transform it will first check that a file exists,
+  if it does nothing further is done, if it does not it tries to add a default
+  Path to the file and search there again. If the file does not exist an error
+  is returned normally but this can be disabled using
+  `CLI::FileOnDefaultPath(default_path, false)`. This allows multiple paths to
+  be chained using multiple transform calls.
  
 ##### Validator operations
  
-Validators are copyable and have a few operations that can be performed on them to alter settings. Most of the built in Validators have a default description that is displayed in the help. This can be altered via `.description(validator_description)`.
-The name of a Validator, which is useful for later reference from the `get_validator(name)` method of an `Option` can be set via `.name(validator_name)`
-The operation function of a Validator can be set via
-`.operation(std::function<std::string(std::string &>)`. The `.active()` function can activate or deactivate a Validator from the operation. A validator can be set to apply only to a specific element of the output. For example in a pair option `std::pair<int, std::string>` the first element may need to be a positive integer while the second may need to be a valid file. The `.application_index(int)` function can specify this. It is zero based and negative indices apply to all values.
+Validators are copyable and have a few operations that can be performed on them
+to alter settings. Most of the built in Validators have a default description
+that is displayed in the help. This can be altered via
+`.description(validator_description)`. The name of a Validator, which is useful
+for later reference from the `get_validator(name)` method of an `Option` can be
+set via `.name(validator_name)` The operation function of a Validator can be set
+via `.operation(std::function<std::string(std::string &>)`. The `.active()`
+function can activate or deactivate a Validator from the operation. A validator
+can be set to apply only to a specific element of the output. For example in a
+pair option `std::pair<int, std::string>` the first element may need to be a
+positive integer while the second may need to be a valid file. The
+`.application_index(int)` function can specify this. It is zero based and
+negative indices apply to all values.
  
 ```cpp
 opt->check(CLI::Validator(CLI::PositiveNumber).application_index(0));
 opt->check(CLI::Validator(CLI::ExistingFile).application_index(1));
 ```
  
-All the validator operation functions return a Validator reference allowing them to be chained. For example
+All the validator operation functions return a Validator reference allowing them
+to be chained. For example
  
 ```cpp
 opt->check(CLI::Range(10,20).description("range is limited to sensible values").active(false).name("range"));
 ```
  
-will specify a check on an option with a name "range", but deactivate it for the time being.
-The check can later be activated through
+will specify a check on an option with a name "range", but deactivate it for the
+time being. The check can later be activated through
  
 ```cpp
 opt->get_validator("range")->active();
@@ -528,7 +829,8 @@ or if the operation function is set later they can be created with
 CLI::Validator(validator_description);
 ```
  
-It is also possible to create a subclass of `CLI::Validator`, in which case it can also set a custom description function, and operation function.
+It is also possible to create a subclass of `CLI::Validator`, in which case it
+can also set a custom description function, and operation function.
  
 ##### Querying Validators
  
@@ -538,7 +840,9 @@ Once loaded into an Option, a pointer to a named Validator can be retrieved via
 opt->get_validator(name);
 ```
  
-This will retrieve a Validator with the given name or throw a `CLI::OptionNotFound` error. If no name is given or name is empty the first unnamed Validator will be returned or the first Validator if there is only one.
+This will retrieve a Validator with the given name or throw a
+`CLI::OptionNotFound` error. If no name is given or name is empty the first
+unnamed Validator will be returned or the first Validator if there is only one.
  
 or
  
@@ -546,108 +850,265 @@ or
 opt->get_validator(index);
 ```
  
-Which will return a validator in the index it is applied which isn't necessarily the order in which was defined. The pointer can be `nullptr` if an invalid index is given.
-Validators have a few functions to query the current values:
+Which will return a validator in the index it is applied which isn't necessarily
+the order in which was defined. The pointer can be `nullptr` if an invalid index
+is given. Validators have a few functions to query the current values:
  
 - `get_description()`: Will return a description string
 - `get_name()`: Will return the Validator name
-- `get_active()`: Will return the current active state, true if the Validator is active.
+- `get_active()`: Will return the current active state, true if the Validator is
+  active.
 - `get_application_index()`: Will return the current application index.
-- `get_modifying()`: Will return true if the Validator is allowed to modify the input, this can be controlled via the `non_modifying()` method, though it is recommended to let `check` and `transform` option methods manipulate it if needed.
+- `get_modifying()`: Will return true if the Validator is allowed to modify the
+  input, this can be controlled via the `non_modifying()` method, though it is
+  recommended to let `check` and `transform` option methods manipulate it if
+  needed.
  
 #### Getting results
  
-In most cases, the fastest and easiest way is to return the results through a callback or variable specified in one of the `add_*` functions. But there are situations where this is not possible or desired. For these cases the results may be obtained through one of the following functions. Please note that these functions will do any type conversions and processing during the call so should not used in performance critical code:
-
-- `->results()`: Retrieves a vector of strings with all the results in the order they were given.
-- `->results(variable_to_bind_to)`: Gets the results according to the MultiOptionPolicy and converts them just like the `add_option_function` with a variable.
-- `Value=opt->as<type>()`: Returns the result or default value directly as the specified type if possible, can be vector to return all results, and a non-vector to get the result according to the MultiOptionPolicy in place.
+In most cases, the fastest and easiest way is to return the results through a
+callback or variable specified in one of the `add_*` functions. But there are
+situations where this is not possible or desired. For these cases the results
+may be obtained through one of the following functions. Please note that these
+functions will do any type conversions and processing during the call so should
+not used in performance critical code:
+
+- `->results()`: Retrieves a vector of strings with all the results in the order
+  they were given.
+- `->results(variable_to_bind_to)`: Gets the results according to the
+  MultiOptionPolicy and converts them just like the `add_option_function` with a
+  variable.
+- `Value=opt->as<type>()`: Returns the result or default value directly as the
+  specified type if possible, can be vector to return all results, and a
+  non-vector to get the result according to the MultiOptionPolicy in place.
  
 ### Subcommands
  
-Subcommands are supported, and can be nested infinitely. To add a subcommand, call the `add_subcommand` method with a name and an optional description. This gives a pointer to an `App` that behaves just like the main app, and can take options or further subcommands. Add `->ignore_case()` to a subcommand to allow any variation of caps to also be accepted. `->ignore_underscore()` is similar, but for underscores. Children inherit the current setting from the parent. You cannot add multiple matching subcommand names at the same level (including `ignore_case` and `ignore_underscore`).
-
-If you want to require that at least one subcommand is given, use `.require_subcommand()` on the parent app. You can optionally give an exact number of subcommands to require, as well. If you give two arguments, that sets the min and max number allowed.
-0 for the max number allowed will allow an unlimited number of subcommands. As a handy shortcut, a single negative value N will set "up to N" values. Limiting the maximum number allows you to keep arguments that match a previous
-subcommand name from matching.
-
-If an `App` (main or subcommand) has been parsed on the command line, `->parsed` will be true (or convert directly to bool).
-All `App`s have a `get_subcommands()` method, which returns a list of pointers to the subcommands passed on the command line. A `got_subcommand(App_or_name)` method is also provided that will check to see if an `App` pointer or a string name was collected on the command line.
-
-For many cases, however, using an app's callback capabilities may be easier. Every app has a set of callbacks that can be executed at various stages of parsing; a `C++` lambda function (with capture to get parsed values) can be used as input to the callback definition function. If you throw `CLI::Success` or `CLI::RuntimeError(return_value)`, you can
-even exit the program through the callback.
-
-Multiple subcommands are allowed, to allow [`Click`][click] like series of commands (order is preserved). The same subcommand can be triggered multiple times but all positional arguments will take precedence over the second and future calls of the subcommand. `->count()` on the subcommand will return the number of times the subcommand was called. The subcommand callback will only be triggered once unless the `.immediate_callback()` flag is set or the callback is specified through the `parse_complete_callback()` function. The `final_callback()` is triggered only once. In which case the callback executes on completion of the subcommand arguments but after the arguments for that subcommand have been parsed, and can be triggered multiple times.
-
-Subcommands may also have an empty name either by calling `add_subcommand` with an empty string for the name or with no arguments.
-Nameless subcommands function a similarly to groups in the main `App`. See [Option groups](#option-groups) to see how this might work. If an option is not defined in the main App, all nameless subcommands are checked as well. This allows for the options to be defined in a composable group. The `add_subcommand` function has an overload for adding a `shared_ptr<App>` so the subcommand(s) could be defined in different components and merged into a main `App`, or possibly multiple `Apps`. Multiple nameless subcommands are allowed. Callbacks for nameless subcommands are only triggered if any options from the subcommand were parsed. Subcommand names given through the `add_subcommand` method have the same restrictions as option names.
+Subcommands are supported, and can be nested infinitely. To add a subcommand,
+call the `add_subcommand` method with a name and an optional description. This
+gives a pointer to an `App` that behaves just like the main app, and can take
+options or further subcommands. Add `->ignore_case()` to a subcommand to allow
+any variation of caps to also be accepted. `->ignore_underscore()` is similar,
+but for underscores. Children inherit the current setting from the parent. You
+cannot add multiple matching subcommand names at the same level (including
+`ignore_case` and `ignore_underscore`).
+
+If you want to require that at least one subcommand is given, use
+`.require_subcommand()` on the parent app. You can optionally give an exact
+number of subcommands to require, as well. If you give two arguments, that sets
+the min and max number allowed. 0 for the max number allowed will allow an
+unlimited number of subcommands. As a handy shortcut, a single negative value N
+will set "up to N" values. Limiting the maximum number allows you to keep
+arguments that match a previous subcommand name from matching.
+
+If an `App` (main or subcommand) has been parsed on the command line, `->parsed`
+will be true (or convert directly to bool). All `App`s have a
+`get_subcommands()` method, which returns a list of pointers to the subcommands
+passed on the command line. A `got_subcommand(App_or_name)` method is also
+provided that will check to see if an `App` pointer or a string name was
+collected on the command line.
+
+For many cases, however, using an app's callback capabilities may be easier.
+Every app has a set of callbacks that can be executed at various stages of
+parsing; a `C++` lambda function (with capture to get parsed values) can be used
+as input to the callback definition function. If you throw `CLI::Success` or
+`CLI::RuntimeError(return_value)`, you can even exit the program through the
+callback.
+
+Multiple subcommands are allowed, to allow [`Click`][click] like series of
+commands (order is preserved). The same subcommand can be triggered multiple
+times but all positional arguments will take precedence over the second and
+future calls of the subcommand. `->count()` on the subcommand will return the
+number of times the subcommand was called. The subcommand callback will only be
+triggered once unless the `.immediate_callback()` flag is set or the callback is
+specified through the `parse_complete_callback()` function. The
+`final_callback()` is triggered only once. In which case the callback executes
+on completion of the subcommand arguments but after the arguments for that
+subcommand have been parsed, and can be triggered multiple times.
+
+Subcommands may also have an empty name either by calling `add_subcommand` with
+an empty string for the name or with no arguments. Nameless subcommands function
+a similarly to groups in the main `App`. See [Option groups](#option-groups) to
+see how this might work. If an option is not defined in the main App, all
+nameless subcommands are checked as well. This allows for the options to be
+defined in a composable group. The `add_subcommand` function has an overload for
+adding a `shared_ptr<App>` so the subcommand(s) could be defined in different
+components and merged into a main `App`, or possibly multiple `Apps`. Multiple
+nameless subcommands are allowed. Callbacks for nameless subcommands are only
+triggered if any options from the subcommand were parsed. Subcommand names given
+through the `add_subcommand` method have the same restrictions as option names.
  
 #### Subcommand options
  
-There are several options that are supported on the main app and subcommands and option_groups. These are:
-
-- `.ignore_case()`: Ignore the case of this subcommand. Inherited by added subcommands, so is usually used on the main `App`.
-- `.ignore_underscore()`: Ignore any underscores in the subcommand name. Inherited by added subcommands, so is usually used on the main `App`.
-- `.allow_windows_style_options()`: Allow command line options to be parsed in the form of `/s /long /file:file_name.ext` This option does not change how options are specified in the `add_option` calls or the ability to process options in the form of `-s --long --file=file_name.ext`.
-- `.fallthrough()`: Allow extra unmatched options and positionals to "fall through" and be matched on a parent option. Subcommands always are allowed to "fall through" as in they will first attempt to match on the current subcommand and if they fail will progressively check parents for matching subcommands.
-- `.configurable()`: Allow the subcommand to be triggered from a configuration file. By default subcommand options in a configuration file do not trigger a subcommand but will just update default values.
-- `.disable()`: Specify that the subcommand is disabled, if given with a bool value it will enable or disable the subcommand or option group.
-- `.disabled_by_default()`: Specify that at the start of parsing the subcommand/option_group should be disabled. This is useful for allowing some Subcommands to trigger others.
-- `.enabled_by_default()`: Specify that at the start of each parse the subcommand/option_group should be enabled. This is useful for allowing some Subcommands to disable others.
-- `.silent()`: Specify that the subcommand is silent meaning that if used it won't show up in the subcommand list. This allows the use of subcommands as modifiers
-- `.validate_positionals()`: Specify that positionals should pass validation before matching. Validation is specified through `transform`, `check`, and `each` for an option. If an argument fails validation it is not an error and matching proceeds to the next available positional or extra arguments.
-- `.validate_optional_arguments()`:🆕 Specify that optional arguments should pass validation before being assigned to an option. Validation is specified through `transform`, `check`, and `each` for an option. If an argument fails validation it is not an error and matching proceeds to the next available positional subcommand or extra arguments.
-- `.excludes(option_or_subcommand)`: If given an option pointer or pointer to another subcommand, these subcommands cannot be given together. In the case of options, if the option is passed the subcommand cannot be used and will generate an error.
-- `.needs(option_or_subcommand)`: If given an option pointer or pointer to another subcommand, the subcommands will require the given option to have been given before this subcommand is validated which occurs prior to execution of any callback or after parsing is completed.
+There are several options that are supported on the main app and subcommands and
+option_groups. These are:
+
+- `.ignore_case()`: Ignore the case of this subcommand. Inherited by added
+  subcommands, so is usually used on the main `App`.
+- `.ignore_underscore()`: Ignore any underscores in the subcommand name.
+  Inherited by added subcommands, so is usually used on the main `App`.
+- `.allow_windows_style_options()`: Allow command line options to be parsed in
+  the form of `/s /long /file:file_name.ext` This option does not change how
+  options are specified in the `add_option` calls or the ability to process
+  options in the form of `-s --long --file=file_name.ext`.
+- `.fallthrough()`: Allow extra unmatched options and positionals to "fall
+  through" and be matched on a parent option. Subcommands always are allowed to
+  "fall through" as in they will first attempt to match on the current
+  subcommand and if they fail will progressively check parents for matching
+  subcommands.
+- `.configurable()`: Allow the subcommand to be triggered from a configuration
+  file. By default subcommand options in a configuration file do not trigger a
+  subcommand but will just update default values.
+- `.disable()`: Specify that the subcommand is disabled, if given with a bool
+  value it will enable or disable the subcommand or option group.
+- `.disabled_by_default()`: Specify that at the start of parsing the
+  subcommand/option_group should be disabled. This is useful for allowing some
+  Subcommands to trigger others.
+- `.enabled_by_default()`: Specify that at the start of each parse the
+  subcommand/option_group should be enabled. This is useful for allowing some
+  Subcommands to disable others.
+- `.silent()`: Specify that the subcommand is silent meaning that if used it
+  won't show up in the subcommand list. This allows the use of subcommands as
+  modifiers
+- `.validate_positionals()`: Specify that positionals should pass validation
+  before matching. Validation is specified through `transform`, `check`, and
+  `each` for an option. If an argument fails validation it is not an error and
+  matching proceeds to the next available positional or extra arguments.
+- `.validate_optional_arguments()`:🆕 Specify that optional arguments should
+  pass validation before being assigned to an option. Validation is specified
+  through `transform`, `check`, and `each` for an option. If an argument fails
+  validation it is not an error and matching proceeds to the next available
+  positional subcommand or extra arguments.
+- `.excludes(option_or_subcommand)`: If given an option pointer or pointer to
+  another subcommand, these subcommands cannot be given together. In the case of
+  options, if the option is passed the subcommand cannot be used and will
+  generate an error.
+- `.needs(option_or_subcommand)`: If given an option pointer or pointer to
+  another subcommand, the subcommands will require the given option to have been
+  given before this subcommand is validated which occurs prior to execution of
+  any callback or after parsing is completed.
 - `.require_option()`: Require 1 or more options or option groups be used.
-- `.require_option(N)`: Require `N` options or option groups, if `N>0`, or up to `N` if `N<0`. `N=0` resets to the default to 0 or more.
-- `.require_option(min, max)`: Explicitly set min and max allowed options or option groups. Setting `max` to 0 implies unlimited options.
+- `.require_option(N)`: Require `N` options or option groups, if `N>0`, or up to
+  `N` if `N<0`. `N=0` resets to the default to 0 or more.
+- `.require_option(min, max)`: Explicitly set min and max allowed options or
+  option groups. Setting `max` to 0 implies unlimited options.
 - `.require_subcommand()`: Require 1 or more subcommands.
-- `.require_subcommand(N)`: Require `N` subcommands if `N>0`, or up to `N` if `N<0`. `N=0` resets to the default to 0 or more.
-- `.require_subcommand(min, max)`: Explicitly set min and max allowed subcommands. Setting `max` to 0 is unlimited.
-- `.add_subcommand(name="", description="")`: Add a subcommand, returns a pointer to the internally stored subcommand.
-- `.add_subcommand(shared_ptr<App>)`: Add a subcommand by shared_ptr, returns a pointer to the internally stored subcommand.
+- `.require_subcommand(N)`: Require `N` subcommands if `N>0`, or up to `N` if
+  `N<0`. `N=0` resets to the default to 0 or more.
+- `.require_subcommand(min, max)`: Explicitly set min and max allowed
+  subcommands. Setting `max` to 0 is unlimited.
+- `.add_subcommand(name="", description="")`: Add a subcommand, returns a
+  pointer to the internally stored subcommand.
+- `.add_subcommand(shared_ptr<App>)`: Add a subcommand by shared_ptr, returns a
+  pointer to the internally stored subcommand.
 - `.remove_subcommand(App)`: Remove a subcommand from the app or subcommand.
-- `.got_subcommand(App_or_name)`: Check to see if a subcommand was received on the command line.
-- `.get_subcommands(filter)`: The list of subcommands that match a particular filter function.
-- `.add_option_group(name="", description="")`: Add an [option group](#option-groups) to an App, an option group is specialized subcommand intended for containing groups of options or other groups for controlling how options interact.
+- `.got_subcommand(App_or_name)`: Check to see if a subcommand was received on
+  the command line.
+- `.get_subcommands(filter)`: The list of subcommands that match a particular
+  filter function.
+- `.add_option_group(name="", description="")`: Add an
+  [option group](#option-groups) to an App, an option group is specialized
+  subcommand intended for containing groups of options or other groups for
+  controlling how options interact.
 - `.get_parent()`: Get the parent App or `nullptr` if called on main App.
-- `.get_option(name)`: Get an option pointer by option name will throw if the specified option is not available, nameless subcommands are also searched
-- `.get_option_no_throw(name)`: Get an option pointer by option name. This function will return a `nullptr` instead of throwing if the option is not available.
-- `.get_options(filter)`: Get the list of all defined option pointers (useful for processing the app for custom output formats).
-- `.parse_order()`: Get the list of option pointers in the order they were parsed (including duplicates).
-- `.formatter(fmt)`: Set a formatter, with signature `std::string(const App*, std::string, AppFormatMode)`. See Formatting for more details.
+- `.get_option(name)`: Get an option pointer by option name will throw if the
+  specified option is not available, nameless subcommands are also searched
+- `.get_option_no_throw(name)`: Get an option pointer by option name. This
+  function will return a `nullptr` instead of throwing if the option is not
+  available.
+- `.get_options(filter)`: Get the list of all defined option pointers (useful
+  for processing the app for custom output formats).
+- `.parse_order()`: Get the list of option pointers in the order they were
+  parsed (including duplicates).
+- `.formatter(fmt)`: Set a formatter, with signature
+  `std::string(const App*, std::string, AppFormatMode)`. See Formatting for more
+  details.
 - `.description(str)`: Set/change the description.
 - `.get_description()`: Access the description.
-- `.alias(str)`: set an alias for the subcommand, this allows subcommands to be called by more than one name.
+- `.alias(str)`: set an alias for the subcommand, this allows subcommands to be
+  called by more than one name.
 - `.parsed()`: True if this subcommand was given on the command line.
 - `.count()`: Returns the number of times the subcommand was called.
-- `.count(option_name)`: Returns the number of times a particular option was called.
-- `.count_all()`: Returns the total number of arguments a particular subcommand processed, on the main App it returns the total number of processed commands.
+- `.count(option_name)`: Returns the number of times a particular option was
+  called.
+- `.count_all()`: Returns the total number of arguments a particular subcommand
+  processed, on the main App it returns the total number of processed commands.
 - `.name(name)`: Add or change the name.
-- `.callback(void() function)`: Set the callback for an app. Either sets the `pre_parse_callback` or the `final_callback` depending on the value of `immediate_callback`. See [Subcommand callbacks](#callbacks) for some additional details.
-- `.parse_complete_callback(void() function)`: Set the callback that runs at the completion of parsing. For subcommands this is executed at the completion of the single subcommand and can be executed multiple times. See [Subcommand callbacks](#callbacks) for some additional details.
-- `.final_callback(void() function)`: Set the callback that runs at the end of all processing. This is the last thing that is executed before returning. See [Subcommand callbacks](#callbacks) for some additional details.
-- `.immediate_callback()`: Specifies whether the callback for a subcommand should be run as a `parse_complete_callback`(true) or `final_callback`(false). When used on the main app it will execute the main app callback prior to the callbacks for a subcommand if they do not also have the `immediate_callback` flag set. It is preferable to use the `parse_complete_callback` or `final_callback` directly instead of the `callback` and `immediate_callback` if one wishes to control the ordering and timing of callback. Though `immediate_callback` can be used to swap them if that is needed.
-- `.pre_parse_callback(void(std::size_t) function)`: Set a callback that executes after the first argument of an application is processed. See [Subcommand callbacks](#callbacks) for some additional details.
+- `.callback(void() function)`: Set the callback for an app. Either sets the
+  `pre_parse_callback` or the `final_callback` depending on the value of
+  `immediate_callback`. See [Subcommand callbacks](#callbacks) for some
+  additional details.
+- `.parse_complete_callback(void() function)`: Set the callback that runs at the
+  completion of parsing. For subcommands this is executed at the completion of
+  the single subcommand and can be executed multiple times. See
+  [Subcommand callbacks](#callbacks) for some additional details.
+- `.final_callback(void() function)`: Set the callback that runs at the end of
+  all processing. This is the last thing that is executed before returning. See
+  [Subcommand callbacks](#callbacks) for some additional details.
+- `.immediate_callback()`: Specifies whether the callback for a subcommand
+  should be run as a `parse_complete_callback`(true) or `final_callback`(false).
+  When used on the main app it will execute the main app callback prior to the
+  callbacks for a subcommand if they do not also have the `immediate_callback`
+  flag set. It is preferable to use the `parse_complete_callback` or
+  `final_callback` directly instead of the `callback` and `immediate_callback`
+  if one wishes to control the ordering and timing of callback. Though
+  `immediate_callback` can be used to swap them if that is needed.
+- `.pre_parse_callback(void(std::size_t) function)`: Set a callback that
+  executes after the first argument of an application is processed. See
+  [Subcommand callbacks](#callbacks) for some additional details.
 - `.allow_extras()`: Do not throw an error if extra arguments are left over.
-- `.positionals_at_end()`: Specify that positional arguments occur as the last arguments and throw an error if an unexpected positional is encountered.
-- `.prefix_command()`: Like `allow_extras`, but stop immediately on the first unrecognized item. It is ideal for allowing your app or subcommand to be a "prefix" to calling another app.
+- `.positionals_at_end()`: Specify that positional arguments occur as the last
+  arguments and throw an error if an unexpected positional is encountered.
+- `.prefix_command()`: Like `allow_extras`, but stop immediately on the first
+  unrecognized item. It is ideal for allowing your app or subcommand to be a
+  "prefix" to calling another app.
 - `.footer(message)`: Set text to appear at the bottom of the help string.
-- `.footer(std::string())`: Set a callback to generate a string that will appear at the end of the help string.
-- `.set_help_flag(name, message)`: Set the help flag name and message, returns a pointer to the created option.
-- `.set_version_flag(name, versionString or callback, help_message)`: Set the version flag name and version string or callback and optional help message, returns a pointer to the created option.
-- `.set_help_all_flag(name, message)`: Set the help all flag name and message, returns a pointer to the created option. Expands subcommands.
-- `.failure_message(func)`: Set the failure message function. Two provided: `CLI::FailureMessage::help` and `CLI::FailureMessage::simple` (the default).
-- `.group(name)`: Set a group name, defaults to `"Subcommands"`. Setting `""` will be hide the subcommand.
-- `[option_name]`: retrieve a const pointer to an option given by `option_name` for Example `app["--flag1"]` will get a pointer to the option for the "--flag1" value, `app["--flag1"]->as<bool>()` will get the results of the command line for a flag. The operation will throw an exception if the option name is not valid.
-
-> Note: if you have a fixed number of required positional options, that will match before subcommand names. `{}` is an empty filter function, and any positional argument will match before repeated subcommand names.
+- `.footer(std::string())`: Set a callback to generate a string that will appear
+  at the end of the help string.
+- `.set_help_flag(name, message)`: Set the help flag name and message, returns a
+  pointer to the created option.
+- `.set_version_flag(name, versionString or callback, help_message)`: Set the
+  version flag name and version string or callback and optional help message,
+  returns a pointer to the created option.
+- `.set_help_all_flag(name, message)`: Set the help all flag name and message,
+  returns a pointer to the created option. Expands subcommands.
+- `.failure_message(func)`: Set the failure message function. Two provided:
+  `CLI::FailureMessage::help` and `CLI::FailureMessage::simple` (the default).
+- `.group(name)`: Set a group name, defaults to `"Subcommands"`. Setting `""`
+  will be hide the subcommand.
+- `[option_name]`: retrieve a const pointer to an option given by `option_name`
+  for Example `app["--flag1"]` will get a pointer to the option for the
+  "--flag1" value, `app["--flag1"]->as<bool>()` will get the results of the
+  command line for a flag. The operation will throw an exception if the option
+  name is not valid.
+
+> Note: if you have a fixed number of required positional options, that will
+> match before subcommand names. `{}` is an empty filter function, and any
+> positional argument will match before repeated subcommand names.
  
 #### Callbacks
  
-A subcommand has three optional callbacks that are executed at different stages of processing. The `preparse_callback` is executed once after the first argument of a subcommand or application is processed and gives an argument for the number of remaining arguments to process. For the main app the first argument is considered the program name, for subcommands the first argument is the subcommand name. For Option groups and nameless subcommands the first argument is after the first argument or subcommand is processed from that group.
-The second callback is executed after parsing. This is known as the `parse_complete_callback`. For subcommands this is executed immediately after parsing and can be executed multiple times if a subcommand is called multiple times. On the main app this callback is executed after all the `parse_complete_callback`s for the subcommands are executed but prior to any `final_callback` calls in the subcommand or option groups. If the main app or subcommand has a config file, no data from the config file will be reflected in `parse_complete_callback` on named subcommands. For `option_group`s the `parse_complete_callback` is executed prior to the `parse_complete_callback` on the main app but after the `config_file` is loaded (if specified). The `final_callback` is executed after all processing is complete. After the `parse_complete_callback` is executed on the main app, the used subcommand `final_callback` are executed followed by the "final callback" for option groups. The last thing to execute is the `final_callback` for the `main_app`.
+A subcommand has three optional callbacks that are executed at different stages
+of processing. The `preparse_callback` is executed once after the first argument
+of a subcommand or application is processed and gives an argument for the number
+of remaining arguments to process. For the main app the first argument is
+considered the program name, for subcommands the first argument is the
+subcommand name. For Option groups and nameless subcommands the first argument
+is after the first argument or subcommand is processed from that group. The
+second callback is executed after parsing. This is known as the
+`parse_complete_callback`. For subcommands this is executed immediately after
+parsing and can be executed multiple times if a subcommand is called multiple
+times. On the main app this callback is executed after all the
+`parse_complete_callback`s for the subcommands are executed but prior to any
+`final_callback` calls in the subcommand or option groups. If the main app or
+subcommand has a config file, no data from the config file will be reflected in
+`parse_complete_callback` on named subcommands. For `option_group`s the
+`parse_complete_callback` is executed prior to the `parse_complete_callback` on
+the main app but after the `config_file` is loaded (if specified). The
+`final_callback` is executed after all processing is complete. After the
+`parse_complete_callback` is executed on the main app, the used subcommand
+`final_callback` are executed followed by the "final callback" for option
+groups. The last thing to execute is the `final_callback` for the `main_app`.
 For example say an application was set up like
  
 ```cpp
@@ -667,22 +1128,30 @@ program --opt1 opt1_val  sub1 --sub1opt --sub1optb val sub2 --sub2opt sub1 --sub
 ```
  
 - `pa` will be called prior to parsing any values with an argument of 13.
-- `pc1` will be called immediately after processing the `sub1` command with a value of 10.
+- `pc1` will be called immediately after processing the `sub1` command with a
+  value of 10.
 - `c1` will be called when the `sub2` command is encountered.
 - `pc2` will be called with value of 6 after the `sub2` command is encountered.
 - `c1` will be called again after the second `sub2` command is encountered.
 - `ac1` will be called after processing of all arguments
 - `c2` will be called once after processing all arguments.
-- `ac2` will be called last after completing all lower level callbacks have been executed.
+- `ac2` will be called last after completing all lower level callbacks have been
+  executed.
  
-A subcommand is considered terminated when one of the following conditions are met.
+A subcommand is considered terminated when one of the following conditions are
+met.
  
 1. There are no more arguments to process
-2. Another subcommand is encountered that would not fit in an optional slot of the subcommand
-3. The `positional_mark` (`--`) is encountered and there are no available positional slots in the subcommand.
+2. Another subcommand is encountered that would not fit in an optional slot of
+   the subcommand
+3. The `positional_mark` (`--`) is encountered and there are no available
+   positional slots in the subcommand.
 4. The `subcommand_terminator` mark (`++`) is encountered
  
-Prior to executed a `parse_complete_callback` all contained options are processed before the callback is triggered. If a subcommand with a `parse_complete_callback` is called again, then the contained options are reset, and can be triggered again.
+Prior to executed a `parse_complete_callback` all contained options are
+processed before the callback is triggered. If a subcommand with a
+`parse_complete_callback` is called again, then the contained options are reset,
+and can be triggered again.
  
 #### Option groups
  
@@ -692,7 +1161,18 @@ The subcommand method
 .add_option_group(name,description)
 ```
  
-Will create an option group, and return a pointer to it. The argument for `description` is optional and can be omitted. An option group allows creation of a collection of options, similar to the groups function on options, but with additional controls and requirements. They allow specific sets of options to be composed and controlled as a collective. For an example see [range example](https://github.com/CLIUtils/CLI11/blob/main/examples/ranges.cpp). Option groups are a specialization of an App so all [functions](#subcommand-options) that work with an App or subcommand also work on option groups. Options can be created as part of an option group using the add functions just like a subcommand, or previously created options can be added through. The name given in an option group must not contain newlines or null characters.
+Will create an option group, and return a pointer to it. The argument for
+`description` is optional and can be omitted. An option group allows creation of
+a collection of options, similar to the groups function on options, but with
+additional controls and requirements. They allow specific sets of options to be
+composed and controlled as a collective. For an example see
+[range example](https://github.com/CLIUtils/CLI11/blob/main/examples/ranges.cpp).
+Option groups are a specialization of an App so all
+[functions](#subcommand-options) that work with an App or subcommand also work
+on option groups. Options can be created as part of an option group using the
+add functions just like a subcommand, or previously created options can be added
+through. The name given in an option group must not contain newlines or null
+characters.
  
 ```cpp
 ogroup->add_option(option_pointer);
@@ -700,49 +1180,75 @@ ogroup-&gt;add_options(option_pointer);
 ogroup->add_options(option1,option2,option3,...);
 ```
  
-The option pointers used in this function must be options defined in the parent application of the option group otherwise an error will be generated. Subcommands can also be added via
+The option pointers used in this function must be options defined in the parent
+application of the option group otherwise an error will be generated.
+Subcommands can also be added via
  
 ```cpp
 ogroup->add_subcommand(subcom_pointer);
 ```
  
-This results in the subcommand being moved from its parent into the option group.
-
-Options in an option group are searched for a command line match after any options in the main app, so any positionals in the main app would be matched first. So care must be taken to make sure of the order when using positional arguments and option groups.
-Option groups work well with `excludes` and `require_options` methods, as an application will treat an option group as a single option for the purpose of counting and requirements, and an option group will be considered used if any of the options or subcommands contained in it are used. Option groups allow specifying requirements such as requiring 1 of 3 options in one group and 1 of 3 options in a different group. Option groups can contain other groups as well. Disabling an option group will turn off all options within the group.
-
-The `CLI::TriggerOn` and `CLI::TriggerOff` methods are helper functions to allow the use of options/subcommands from one group to trigger another group on or off.
+This results in the subcommand being moved from its parent into the option
+group.
+
+Options in an option group are searched for a command line match after any
+options in the main app, so any positionals in the main app would be matched
+first. So care must be taken to make sure of the order when using positional
+arguments and option groups. Option groups work well with `excludes` and
+`require_options` methods, as an application will treat an option group as a
+single option for the purpose of counting and requirements, and an option group
+will be considered used if any of the options or subcommands contained in it are
+used. Option groups allow specifying requirements such as requiring 1 of 3
+options in one group and 1 of 3 options in a different group. Option groups can
+contain other groups as well. Disabling an option group will turn off all
+options within the group.
+
+The `CLI::TriggerOn` and `CLI::TriggerOff` methods are helper functions to allow
+the use of options/subcommands from one group to trigger another group on or
+off.
  
 ```cpp
 CLI::TriggerOn(group1_pointer, triggered_group);
 CLI::TriggerOff(group2_pointer, disabled_group);
 ```
  
-These functions make use of `preparse_callback`, `enabled_by_default()` and `disabled_by_default`. The triggered group may be a vector of group pointers. These methods should only be used once per group and will override any previous use of the underlying functions. More complex arrangements can be accomplished using similar methodology with a custom `preparse_callback` function that does more.
+These functions make use of `preparse_callback`, `enabled_by_default()` and
+`disabled_by_default`. The triggered group may be a vector of group pointers.
+These methods should only be used once per group and will override any previous
+use of the underlying functions. More complex arrangements can be accomplished
+using similar methodology with a custom `preparse_callback` function that does
+more.
  
-Additional helper functions `deprecate_option` and `retire_option` are available to deprecate or retire options
+Additional helper functions `deprecate_option` and `retire_option` are available
+to deprecate or retire options
  
 ```cpp
 CLI::deprecate_option(option *, replacement_name="");
 CLI::deprecate_option(App,option_name,replacement_name="");
 ```
  
-will specify that the option is deprecated which will display a message in the help and a warning on first usage. Deprecated options function normally but will add a message in the help and display a warning on first use.
+will specify that the option is deprecated which will display a message in the
+help and a warning on first usage. Deprecated options function normally but will
+add a message in the help and display a warning on first use.
  
 ```cpp
 CLI::retire_option(App,option *);
 CLI::retire_option(App,option_name);
 ```
  
-will create an option that does nothing by default and will display a warning on first usage that the option is retired and has no effect. If the option exists it is replaces with a dummy option that takes the same arguments.
+will create an option that does nothing by default and will display a warning on
+first usage that the option is retired and has no effect. If the option exists
+it is replaces with a dummy option that takes the same arguments.
  
-If an empty string is passed the option group name the entire group will be hidden in the help results. For example.
+If an empty string is passed the option group name the entire group will be
+hidden in the help results. For example.
  
 ```cpp
 auto hidden_group=app.add_option_group("");
 ```
  
-will create a group such that no options in that group are displayed in the help string.
+will create a group such that no options in that group are displayed in the help
+string.
  
 ### Configuration file
  
@@ -753,7 +1259,16 @@ app.set_config(option_name=&quot;&quot;,
                required=false)
 ```
  
-If this is called with no arguments, it will remove the configuration file option (like `set_help_flag`). Setting a configuration option is special. If it is present, it will be read along with the normal command line arguments. The file will be read if it exists, and does not throw an error unless `required` is `true`. Configuration files are in [TOML][] format by default, though the default reader can also accept files in INI format as well. It should be noted that CLI11 does not contain a full TOML parser but can read strings from most TOML file and run them through the CLI11 parser. Other formats can be added by an adept user, some variations are available through customization points in the default formatter. An example of a TOML file:
+If this is called with no arguments, it will remove the configuration file
+option (like `set_help_flag`). Setting a configuration option is special. If it
+is present, it will be read along with the normal command line arguments. The
+file will be read if it exists, and does not throw an error unless `required` is
+`true`. Configuration files are in [TOML][] format by default, though the
+default reader can also accept files in INI format as well. It should be noted
+that CLI11 does not contain a full TOML parser but can read strings from most
+TOML file and run them through the CLI11 parser. Other formats can be added by
+an adept user, some variations are available through customization points in the
+default formatter. An example of a TOML file:
  
 ```toml
 # Comments are supported, using a #
@@ -787,10 +1302,23 @@ in_subcommand = Wow
 sub.subcommand = true
 ```
  
-Spaces before and after the name and argument are ignored. Multiple arguments are separated by spaces. One set of quotes will be removed, preserving spaces (the same way the command line works). Boolean options can be `true`, `on`, `1`, `yes`, `enable`; or `false`, `off`, `0`, `no`, `disable` (case insensitive). Sections (and `.` separated names) are treated as subcommands (note: this does not necessarily mean that subcommand was passed, it just sets the "defaults"). You cannot set positional-only arguments. Subcommands can be triggered from configuration files if the `configurable` flag was set on the subcommand. Then the use of `[subcommand]` notation will trigger a subcommand and cause it to act as if it were on the command line.
-
-To print a configuration file from the passed
-arguments, use `.config_to_str(default_also=false, write_description=false)`, where `default_also` will also show any defaulted arguments, and `write_description` will include the app and option descriptions. See [Config files](https://cliutils.github.io/CLI11/book/chapters/config.html) for some additional details and customization points.
+Spaces before and after the name and argument are ignored. Multiple arguments
+are separated by spaces. One set of quotes will be removed, preserving spaces
+(the same way the command line works). Boolean options can be `true`, `on`, `1`,
+`yes`, `enable`; or `false`, `off`, `0`, `no`, `disable` (case insensitive).
+Sections (and `.` separated names) are treated as subcommands (note: this does
+not necessarily mean that subcommand was passed, it just sets the "defaults").
+You cannot set positional-only arguments. Subcommands can be triggered from
+configuration files if the `configurable` flag was set on the subcommand. Then
+the use of `[subcommand]` notation will trigger a subcommand and cause it to act
+as if it were on the command line.
+
+To print a configuration file from the passed arguments, use
+`.config_to_str(default_also=false, write_description=false)`, where
+`default_also` will also show any defaulted arguments, and `write_description`
+will include the app and option descriptions. See
+[Config files](https://cliutils.github.io/CLI11/book/chapters/config.html) for
+some additional details and customization points.
  
 If it is desired that multiple configuration be allowed. Use
  
@@ -798,23 +1326,42 @@ If it is desired that multiple configuration be allowed. Use
 app.set_config("--config")->expected(1, X);
 ```
  
-Where X is some positive number and will allow up to `X` configuration files to be specified by separate `--config` arguments. Value strings with quote characters in it will be printed with a single quote. All other arguments will use double quote. Empty strings will use a double quoted argument. Numerical or boolean values are not quoted.
+Where X is some positive number and will allow up to `X` configuration files to
+be specified by separate `--config` arguments. Value strings with quote
+characters in it will be printed with a single quote. All other arguments will
+use double quote. Empty strings will use a double quoted argument. Numerical or
+boolean values are not quoted.
  
-For options or flags which allow 0 arguments to be passed using an empty string in the config file, `{}`, or `[]` will convert the result to the default value specified via `default_str` or `default_val` on the option 🆕. If no user specified default is given the result is an empty string or the converted value of an empty string.
+For options or flags which allow 0 arguments to be passed using an empty string
+in the config file, `{}`, or `[]` will convert the result to the default value
+specified via `default_str` or `default_val` on the option 🆕. If no user
+specified default is given the result is an empty string or the converted value
+of an empty string.
  
-NOTE: Transforms and checks can be used with the option pointer returned from set_config like any other option to validate the input if needed. It can also be used with the built in transform `CLI::FileOnDefaultPath` to look in a default path as well as the current one. For example
+NOTE: Transforms and checks can be used with the option pointer returned from
+set_config like any other option to validate the input if needed. It can also be
+used with the built in transform `CLI::FileOnDefaultPath` to look in a default
+path as well as the current one. For example
  
 ```cpp
 app.set_config("--config")->transform(CLI::FileOnDefaultPath("/to/default/path/"));
 ```
  
-See [Transforming Validators](#transforming-validators) for additional details on this validator. Multiple transforms or validators can be used either by multiple calls or using `|` operations with the transform.
+See [Transforming Validators](#transforming-validators) for additional details
+on this validator. Multiple transforms or validators can be used either by
+multiple calls or using `|` operations with the transform.
  
 ### Inheriting defaults
  
-Many of the defaults for subcommands and even options are inherited from their creators. The inherited default values for subcommands are `allow_extras`, `prefix_command`, `ignore_case`, `ignore_underscore`, `fallthrough`, `group`, `footer`,`immediate_callback` and maximum number of required subcommands. The help flag existence, name, and description are inherited, as well.
+Many of the defaults for subcommands and even options are inherited from their
+creators. The inherited default values for subcommands are `allow_extras`,
+`prefix_command`, `ignore_case`, `ignore_underscore`, `fallthrough`, `group`,
+`footer`,`immediate_callback` and maximum number of required subcommands. The
+help flag existence, name, and description are inherited, as well.
  
-Options have defaults for `group`, `required`, `multi_option_policy`, `ignore_case`, `ignore_underscore`, `delimiter`, and `disable_flag_override`. To set these defaults, you should set the `option_defaults()` object, for example:
+Options have defaults for `group`, `required`, `multi_option_policy`,
+`ignore_case`, `ignore_underscore`, `delimiter`, and `disable_flag_override`. To
+set these defaults, you should set the `option_defaults()` object, for example:
  
 ```cpp
 app.option_defaults()->required();
@@ -825,32 +1372,74 @@ The default settings for options are inherited to subcommands, as well.
  
 ### Formatting
  
-The job of formatting help printouts is delegated to a formatter callable object on Apps and Options. You are free to replace either formatter by calling `formatter(fmt)` on an `App`, where fmt is any copyable callable with the correct signature.
-CLI11 comes with a default App formatter functional, `Formatter`. It is customizable; you can set `label(key, value)` to replace the default labels like `REQUIRED`, and `column_width(n)` to set the width of the columns before you add the functional to the app or option. You can also override almost any stage of the formatting process in a subclass of either formatter. If you want to make a new formatter from scratch, you can do
-that too; you just need to implement the correct signature. The first argument is a const pointer to the in question. The formatter will get a `std::string` usage name as the second option, and a `AppFormatMode` mode for the final option. It should return a `std::string`.
-
-The `AppFormatMode` can be `Normal`, `All`, or `Sub`, and it indicates the situation the help was called in. `Sub` is optional, but the default formatter uses it to make sure expanded subcommands are called with
-their own formatter since you can't access anything but the call operator once a formatter has been set.
+The job of formatting help printouts is delegated to a formatter callable object
+on Apps and Options. You are free to replace either formatter by calling
+`formatter(fmt)` on an `App`, where fmt is any copyable callable with the
+correct signature. CLI11 comes with a default App formatter functional,
+`Formatter`. It is customizable; you can set `label(key, value)` to replace the
+default labels like `REQUIRED`, and `column_width(n)` to set the width of the
+columns before you add the functional to the app or option. You can also
+override almost any stage of the formatting process in a subclass of either
+formatter. If you want to make a new formatter from scratch, you can do that
+too; you just need to implement the correct signature. The first argument is a
+const pointer to the in question. The formatter will get a `std::string` usage
+name as the second option, and a `AppFormatMode` mode for the final option. It
+should return a `std::string`.
+
+The `AppFormatMode` can be `Normal`, `All`, or `Sub`, and it indicates the
+situation the help was called in. `Sub` is optional, but the default formatter
+uses it to make sure expanded subcommands are called with their own formatter
+since you can't access anything but the call operator once a formatter has been
+set.
  
 ### Subclassing
  
-The App class was designed allow toolkits to subclass it, to provide preset default options (see above) and setup/teardown code. Subcommands remain an unsubclassed `App`, since those are not expected to need setup and teardown. The default `App` only adds a help flag, `-h,--help`, than can removed/replaced using `.set_help_flag(name, help_string)`. You can also set a help-all flag with `.set_help_all_flag(name, help_string)`; this will expand the subcommands (one level only). You can remove options if you have pointers to them using `.remove_option(opt)`. You can add a `pre_callback` override to customize the after parse
-but before run behavior, while
-still giving the user freedom to `callback` on the main app.
-
-The most important parse function is `parse(std::vector<std::string>)`, which takes a reversed list of arguments (so that `pop_back` processes the args in the correct order). `get_help_ptr` and `get_config_ptr` give you access to the help/config option pointers. The standard `parse` manually sets the name from the first argument, so it should not be in this vector. You can also use `parse(string, bool)` to split up and parse a single string; the optional boolean should be set to true if you are
-including the program name in the string, and false otherwise. The program name can contain spaces if it is an existing file, otherwise can be enclosed in quotes(single quote, double quote or backtick). Embedded quote characters can be escaped with `\`.
-
-Also, in a related note, the `App` you get a pointer to is stored in the parent `App` in a `shared_ptr`s (similar to `Option`s) and are deleted when the main `App` goes out of scope unless the object has another owner.
+The App class was designed allow toolkits to subclass it, to provide preset
+default options (see above) and setup/teardown code. Subcommands remain an
+unsubclassed `App`, since those are not expected to need setup and teardown. The
+default `App` only adds a help flag, `-h,--help`, than can removed/replaced
+using `.set_help_flag(name, help_string)`. You can also set a help-all flag with
+`.set_help_all_flag(name, help_string)`; this will expand the subcommands (one
+level only). You can remove options if you have pointers to them using
+`.remove_option(opt)`. You can add a `pre_callback` override to customize the
+after parse but before run behavior, while still giving the user freedom to
+`callback` on the main app.
+
+The most important parse function is `parse(std::vector<std::string>)`, which
+takes a reversed list of arguments (so that `pop_back` processes the args in the
+correct order). `get_help_ptr` and `get_config_ptr` give you access to the
+help/config option pointers. The standard `parse` manually sets the name from
+the first argument, so it should not be in this vector. You can also use
+`parse(string, bool)` to split up and parse a single string; the optional
+boolean should be set to true if you are including the program name in the
+string, and false otherwise. The program name can contain spaces if it is an
+existing file, otherwise can be enclosed in quotes(single quote, double quote or
+backtick). Embedded quote characters can be escaped with `\`.
+
+Also, in a related note, the `App` you get a pointer to is stored in the parent
+`App` in a `shared_ptr`s (similar to `Option`s) and are deleted when the main
+`App` goes out of scope unless the object has another owner.
  
 ### How it works
  
-Every `add_` option you have seen so far depends on one method that takes a lambda function. Each of these methods is just making a different lambda function with capture to populate the option. The function has full access to the vector of strings, so it knows how many times an option was passed or how many arguments it received. The lambda returns `true` if it could validate the option strings, and
-`false` if it failed.
-
-Other values can be added as long as they support `operator>>` (and defaults can be printed if they support `operator<<`). To add a new type, for example, provide a custom `operator>>` with an `istream` (inside the CLI namespace is fine if you don't want to interfere with an existing `operator>>`).
-
-If you wanted to extend this to support a completely new type, use a lambda or add a specialization of the `lexical_cast` function template in the namespace of the type you need to convert to. Some examples of some new parsers for `complex<double>` that support all of the features of a standard `add_options` call are in [one of the tests](./tests/NewParseTest.cpp). A simpler example is shown below:
+Every `add_` option you have seen so far depends on one method that takes a
+lambda function. Each of these methods is just making a different lambda
+function with capture to populate the option. The function has full access to
+the vector of strings, so it knows how many times an option was passed or how
+many arguments it received. The lambda returns `true` if it could validate the
+option strings, and `false` if it failed.
+
+Other values can be added as long as they support `operator>>` (and defaults can
+be printed if they support `operator<<`). To add a new type, for example,
+provide a custom `operator>>` with an `istream` (inside the CLI namespace is
+fine if you don't want to interfere with an existing `operator>>`).
+
+If you wanted to extend this to support a completely new type, use a lambda or
+add a specialization of the `lexical_cast` function template in the namespace of
+the type you need to convert to. Some examples of some new parsers for
+`complex<double>` that support all of the features of a standard `add_options`
+call are in [one of the tests](./tests/NewParseTest.cpp). A simpler example is
+shown below:
  
 #### Example
  
@@ -863,7 +1452,10 @@ app.add_option(&quot;--fancy-count&quot;, [](std::vector&lt;std::string&gt; val){
  
 ### Utilities
  
-There are a few other utilities that are often useful in CLI programming. These are in separate headers, and do not appear in `CLI11.hpp`, but are completely independent and can be used as needed. The `Timer`/`AutoTimer` class allows you to easily time a block of code, with custom print output.
+There are a few other utilities that are often useful in CLI programming. These
+are in separate headers, and do not appear in `CLI11.hpp`, but are completely
+independent and can be used as needed. The `Timer`/`AutoTimer` class allows you
+to easily time a block of code, with custom print output.
  
 ```cpp
 {
@@ -872,12 +1464,18 @@ some_long_running_process();
 }
 ```
  
-This will create a timer with a title (default: `Timer`), and will customize the output using the predefined `Big` output (default: `Simple`). Because it is an `AutoTimer`, it will print out the time elapsed when the timer is destroyed at the end of the block. If you use `Timer` instead, you can use `to_string` or `std::cout << timer << std::endl;` to print the time. The print function can be any function that takes two strings, the title and the time, and returns a formatted
-string for printing.
+This will create a timer with a title (default: `Timer`), and will customize the
+output using the predefined `Big` output (default: `Simple`). Because it is an
+`AutoTimer`, it will print out the time elapsed when the timer is destroyed at
+the end of the block. If you use `Timer` instead, you can use `to_string` or
+`std::cout << timer << std::endl;` to print the time. The print function can be
+any function that takes two strings, the title and the time, and returns a
+formatted string for printing.
  
 ### Other libraries
  
-If you use the excellent [Rang][] library to add color to your terminal in a safe, multi-platform way, you can combine it with CLI11 nicely:
+If you use the excellent [Rang][] library to add color to your terminal in a
+safe, multi-platform way, you can combine it with CLI11 nicely:
  
 ```cpp
 std::atexit([](){std::cout << rang::style::reset;});
@@ -889,9 +1487,11 @@ try {
 }
 ```
  
-This will print help in blue, errors in red, and will reset before returning the terminal to the user.
+This will print help in blue, errors in red, and will reset before returning the
+terminal to the user.
  
-If you are on a Unix-like system, and you'd like to handle control-c and color, you can add:
+If you are on a Unix-like system, and you'd like to handle control-c and color,
+you can add:
  
 ```cpp
  #include <csignal>
@@ -915,41 +1515,88 @@ And, in your main function:
  
 ## API
  
-The API is [documented here][api-docs]. Also see the [CLI11 tutorial GitBook][gitbook].
+The API is [documented here][api-docs]. Also see the [CLI11 tutorial
+GitBook][gitbook].
  
 ## Examples
  
-Several short examples of different features are included in the repository. A brief description of each is included here
-
-- [callback_passthrough](https://github.com/CLIUtils/CLI11/blob/main/examples/callback_passthrough.cpp): Example of directly passing remaining arguments through to a callback function which generates a CLI11 application based on existing arguments.
-- [custom_parse](https://github.com/CLIUtils/CLI11/blob/main/examples/custom_parse.cpp): Based on [Issue #566](https://github.com/CLIUtils/CLI11/issues/566), example of custom parser
-- [digit_args](https://github.com/CLIUtils/CLI11/blob/main/examples/digit_args.cpp): Based on [Issue #123](https://github.com/CLIUtils/CLI11/issues/123), uses digit flags to pass a value
-- [enum](https://github.com/CLIUtils/CLI11/blob/main/examples/enum.cpp): Using enumerations in an option, and the use of [CheckedTransformer](#transforming-validators)
-- [enum_ostream](https://github.com/CLIUtils/CLI11/blob/main/examples/enum_ostream.cpp): In addition to the contents of example enum.cpp, this example shows how a custom ostream operator overrides CLI11's enum streaming.
-- [formatter](https://github.com/CLIUtils/CLI11/blob/main/examples/formatter.cpp): Illustrating usage of a custom formatter
-- [groups](https://github.com/CLIUtils/CLI11/blob/main/examples/groups.cpp): Example using groups of options for help grouping and a the timer helper class
-- [inter_argument_order](https://github.com/CLIUtils/CLI11/blob/main/examples/inter_argument_order.cpp): An app to practice mixing unlimited arguments, but still recover the original order.
-- [json](https://github.com/CLIUtils/CLI11/blob/main/examples/json.cpp): Using JSON as a config file parser
-- [modhelp](https://github.com/CLIUtils/CLI11/blob/main/examples/modhelp.cpp): How to modify the help flag to do something other than default
-- [nested](https://github.com/CLIUtils/CLI11/blob/main/examples/nested.cpp): Nested subcommands
-- [option_groups](https://github.com/CLIUtils/CLI11/blob/main/examples/option_groups.cpp): Illustrating the use of option groups and a required number of options. Based on [Issue #88](https://github.com/CLIUtils/CLI11/issues/88) to set interacting groups of options
-- [positional_arity](https://github.com/CLIUtils/CLI11/blob/main/examples/positional_arity.cpp): Illustrating use of `preparse_callback` to handle situations where the number of arguments can determine which should get parsed, Based on [Issue #166](https://github.com/CLIUtils/CLI11/issues/166)
-- [positional_validation](https://github.com/CLIUtils/CLI11/blob/main/examples/positional_validation.cpp): Example of how positional arguments are validated using the `validate_positional` flag, also based on [Issue #166](https://github.com/CLIUtils/CLI11/issues/166)
-- [prefix_command](https://github.com/CLIUtils/CLI11/blob/main/examples/prefix_command.cpp): Illustrating use of the `prefix_command` flag.
-- [ranges](https://github.com/CLIUtils/CLI11/blob/main/examples/ranges.cpp): App to demonstrate exclusionary option groups based on [Issue #88](https://github.com/CLIUtils/CLI11/issues/88)
-- [shapes](https://github.com/CLIUtils/CLI11/blob/main/examples/shapes.cpp): Illustrating how to set up repeated subcommands Based on [gitter discussion](https://gitter.im/CLI11gitter/Lobby?at=5c7af6b965ffa019ea788cd5)
-- [simple](https://github.com/CLIUtils/CLI11/blob/main/examples/simple.cpp): A simple example of how to set up a CLI11 Application with different flags and options
-- [subcom_help](https://github.com/CLIUtils/CLI11/blob/main/examples/subcom_help.cpp): Configuring help for subcommands
-- [subcom_partitioned](https://github.com/CLIUtils/CLI11/blob/main/examples/subcom_partitioned.cpp): Example with a timer and subcommands generated separately and added to the main app later.
-- [subcommands](https://github.com/CLIUtils/CLI11/blob/main/examples/subcommands.cpp): Short example of subcommands
-- [validators](https://github.com/CLIUtils/CLI11/blob/main/examples/validators.cpp): Example illustrating use of validators
+Several short examples of different features are included in the repository. A
+brief description of each is included here
+
+- [callback_passthrough](https://github.com/CLIUtils/CLI11/blob/main/examples/callback_passthrough.cpp):
+  Example of directly passing remaining arguments through to a callback function
+  which generates a CLI11 application based on existing arguments.
+- [custom_parse](https://github.com/CLIUtils/CLI11/blob/main/examples/custom_parse.cpp):
+  Based on [Issue #566](https://github.com/CLIUtils/CLI11/issues/566), example
+  of custom parser
+- [digit_args](https://github.com/CLIUtils/CLI11/blob/main/examples/digit_args.cpp):
+  Based on [Issue #123](https://github.com/CLIUtils/CLI11/issues/123), uses
+  digit flags to pass a value
+- [enum](https://github.com/CLIUtils/CLI11/blob/main/examples/enum.cpp): Using
+  enumerations in an option, and the use of
+  [CheckedTransformer](#transforming-validators)
+- [enum_ostream](https://github.com/CLIUtils/CLI11/blob/main/examples/enum_ostream.cpp):
+  In addition to the contents of example enum.cpp, this example shows how a
+  custom ostream operator overrides CLI11's enum streaming.
+- [formatter](https://github.com/CLIUtils/CLI11/blob/main/examples/formatter.cpp):
+  Illustrating usage of a custom formatter
+- [groups](https://github.com/CLIUtils/CLI11/blob/main/examples/groups.cpp):
+  Example using groups of options for help grouping and a the timer helper class
+- [inter_argument_order](https://github.com/CLIUtils/CLI11/blob/main/examples/inter_argument_order.cpp):
+  An app to practice mixing unlimited arguments, but still recover the original
+  order.
+- [json](https://github.com/CLIUtils/CLI11/blob/main/examples/json.cpp): Using
+  JSON as a config file parser
+- [modhelp](https://github.com/CLIUtils/CLI11/blob/main/examples/modhelp.cpp):
+  How to modify the help flag to do something other than default
+- [nested](https://github.com/CLIUtils/CLI11/blob/main/examples/nested.cpp):
+  Nested subcommands
+- [option_groups](https://github.com/CLIUtils/CLI11/blob/main/examples/option_groups.cpp):
+  Illustrating the use of option groups and a required number of options. Based
+  on [Issue #88](https://github.com/CLIUtils/CLI11/issues/88) to set interacting
+  groups of options
+- [positional_arity](https://github.com/CLIUtils/CLI11/blob/main/examples/positional_arity.cpp):
+  Illustrating use of `preparse_callback` to handle situations where the number
+  of arguments can determine which should get parsed, Based on
+  [Issue #166](https://github.com/CLIUtils/CLI11/issues/166)
+- [positional_validation](https://github.com/CLIUtils/CLI11/blob/main/examples/positional_validation.cpp):
+  Example of how positional arguments are validated using the
+  `validate_positional` flag, also based on
+  [Issue #166](https://github.com/CLIUtils/CLI11/issues/166)
+- [prefix_command](https://github.com/CLIUtils/CLI11/blob/main/examples/prefix_command.cpp):
+  Illustrating use of the `prefix_command` flag.
+- [ranges](https://github.com/CLIUtils/CLI11/blob/main/examples/ranges.cpp): App
+  to demonstrate exclusionary option groups based on
+  [Issue #88](https://github.com/CLIUtils/CLI11/issues/88)
+- [shapes](https://github.com/CLIUtils/CLI11/blob/main/examples/shapes.cpp):
+  Illustrating how to set up repeated subcommands Based on
+  [gitter discussion](https://gitter.im/CLI11gitter/Lobby?at=5c7af6b965ffa019ea788cd5)
+- [simple](https://github.com/CLIUtils/CLI11/blob/main/examples/simple.cpp): A
+  simple example of how to set up a CLI11 Application with different flags and
+  options
+- [subcom_help](https://github.com/CLIUtils/CLI11/blob/main/examples/subcom_help.cpp):
+  Configuring help for subcommands
+- [subcom_partitioned](https://github.com/CLIUtils/CLI11/blob/main/examples/subcom_partitioned.cpp):
+  Example with a timer and subcommands generated separately and added to the
+  main app later.
+- [subcommands](https://github.com/CLIUtils/CLI11/blob/main/examples/subcommands.cpp):
+  Short example of subcommands
+- [validators](https://github.com/CLIUtils/CLI11/blob/main/examples/validators.cpp):
+  Example illustrating use of validators
  
 ## Contribute
  
-To contribute, open an [issue][github issues] or [pull request][github pull requests] on GitHub, or ask a question on [gitter][]. There is also a short note to contributors [here](./.github/CONTRIBUTING.md).
-This readme roughly follows the [Standard Readme Style][] and includes a mention of almost every feature of the library. More complex features are documented in more detail in the [CLI11 tutorial GitBook][gitbook].
+To contribute, open an [issue][github issues] or [pull
+request][github pull requests] on GitHub, or ask a question on [gitter][]. There
+is also a short note to contributors [here](./.github/CONTRIBUTING.md). This
+readme roughly follows the [Standard Readme Style][] and includes a mention of
+almost every feature of the library. More complex features are documented in
+more detail in the [CLI11 tutorial GitBook][gitbook].
  
-This project was created by [Henry Schreiner](https://github.com/henryiii) and major features were added by [Philip Top](https://github.com/phlptp). Special thanks to all the contributors ([emoji key](https://allcontributors.org/docs/en/emoji-key)):
+This project was created by [Henry Schreiner](https://github.com/henryiii) and
+major features were added by [Philip Top](https://github.com/phlptp). Special
+thanks to all the contributors
+([emoji key](https://allcontributors.org/docs/en/emoji-key)):
  
 <!-- ALL-CONTRIBUTORS-LIST:START - Do not remove or modify this section -->
 <!-- prettier-ignore-start -->
@@ -1028,25 +1675,35 @@ This project was created by [Henry Schreiner](https://github.com/henryiii) and m
  
 <!-- ALL-CONTRIBUTORS-LIST:END -->
  
-This project follows the [all-contributors](https://github.com/all-contributors/all-contributors) specification. Contributions of any kind welcome!
+This project follows the
+[all-contributors](https://github.com/all-contributors/all-contributors)
+specification. Contributions of any kind welcome!
  
 ## License
  
-As of version 1.0, this library is available under a 3-Clause BSD license. See the [LICENSE](./LICENSE) file for details.
+As of version 1.0, this library is available under a 3-Clause BSD license. See
+the [LICENSE](./LICENSE) file for details.
  
-CLI11 was developed at the [University of Cincinnati][] to support of the [GooFit][] library under [NSF Award 1414736][]. Version 0.9 was featured in a [DIANA/HEP][] meeting at CERN ([see the slides][diana slides]). Please give it a try! Feedback is always welcome.
+CLI11 was developed at the [University of Cincinnati][] to support of the
+[GooFit][] library under [NSF Award 1414736][]. Version 0.9 was featured in a
+[DIANA/HEP][] meeting at CERN ([see the slides][diana slides]). Please give it a
+try! Feedback is always welcome.
  
 [doi-badge]: https://zenodo.org/badge/80064252.svg
 [doi-link]: https://zenodo.org/badge/latestdoi/80064252
-[azure-badge]: https://dev.azure.com/CLIUtils/CLI11/_apis/build/status/CLIUtils.CLI11?branchName=main
+[azure-badge]:
+  https://dev.azure.com/CLIUtils/CLI11/_apis/build/status/CLIUtils.CLI11?branchName=main
 [azure]: https://dev.azure.com/CLIUtils/CLI11
 [actions-link]: https://github.com/CLIUtils/CLI11/actions
-[actions-badge]: https://github.com/CLIUtils/CLI11/actions/workflows/tests.yml/badge.svg
-[appveyor-badge]: https://ci.appveyor.com/api/projects/status/82niaxpaa28dwbms/branch/main?svg=true
+[actions-badge]:
+  https://github.com/CLIUtils/CLI11/actions/workflows/tests.yml/badge.svg
+[appveyor-badge]:
+  https://ci.appveyor.com/api/projects/status/82niaxpaa28dwbms/branch/main?svg=true
 [appveyor]: https://ci.appveyor.com/project/HenrySchreiner/cli11
 [repology-badge]: https://repology.org/badge/latest-versions/cli11.svg
 [repology]: https://repology.org/project/cli11/versions
-[codecov-badge]: https://codecov.io/gh/CLIUtils/CLI11/branch/main/graph/badge.svg?token=2O4wfs8NJO
+[codecov-badge]:
+  https://codecov.io/gh/CLIUtils/CLI11/branch/main/graph/badge.svg?token=2O4wfs8NJO
 [codecov]: https://codecov.io/gh/CLIUtils/CLI11
 [gitter-badge]: https://badges.gitter.im/CLI11gitter/Lobby.svg
 [gitter]: https://gitter.im/CLI11gitter/Lobby
@@ -1063,7 +1720,8 @@ CLI11 was developed at the [University of Cincinnati][] to support of the [GooFi
 [click]: http://click.pocoo.org
 [api-docs]: https://CLIUtils.github.io/CLI11/index.html
 [rang]: https://github.com/agauniyal/rang
-[boost program options]: http://www.boost.org/doc/libs/1_63_0/doc/html/program_options.html
+[boost program options]:
+  http://www.boost.org/doc/libs/1_63_0/doc/html/program_options.html
 [the lean mean c++ option parser]: http://optionparser.sourceforge.net
 [tclap]: http://tclap.sourceforge.net
 [cxxopts]: https://github.com/jarro2783/cxxopts
@@ -1074,7 +1732,8 @@ CLI11 was developed at the [University of Cincinnati][] to support of the [GooFi
 [nsf award 1414736]: https://nsf.gov/awardsearch/showAward?AWD_ID=1414736
 [university of cincinnati]: http://www.uc.edu
 [gitbook]: https://cliutils.github.io/CLI11/book/
-[cli11 advanced topics/custom converters]: https://cliutils.gitlab.io/CLI11Tutorial/chapters/advanced-topics.html#custom-converters
+[cli11 advanced topics/custom converters]:
+  https://cliutils.gitlab.io/CLI11Tutorial/chapters/advanced-topics.html#custom-converters
 [programoptions.hxx]: https://github.com/Fytch/ProgramOptions.hxx
 [argument aggregator]: https://github.com/vietjtnguyen/argagg
 [args]: https://github.com/Taywee/args
@@ -1089,13 +1748,18 @@ CLI11 was developed at the [University of Cincinnati][] to support of the [GooFi
 [wandbox-badge]: https://img.shields.io/badge/try_2.1-online-blue.svg
 [wandbox-link]: https://wandbox.org/permlink/CA5bymNHh0AczdeN
 [releases-badge]: https://img.shields.io/github/release/CLIUtils/CLI11.svg
-[cli11-po-compare]: https://iscinumpy.gitlab.io/post/comparing-cli11-and-boostpo/
-[diana slides]: https://indico.cern.ch/event/619465/contributions/2507949/attachments/1448567/2232649/20170424-diana-2.pdf
+[cli11-po-compare]:
+  https://iscinumpy.gitlab.io/post/comparing-cli11-and-boostpo/
+[diana slides]:
+  https://indico.cern.ch/event/619465/contributions/2507949/attachments/1448567/2232649/20170424-diana-2.pdf
 [awesome c++]: https://github.com/fffaraz/awesome-cpp/blob/master/README.md#cli
 [cli]: https://codesynthesis.com/projects/cli/
-[single file libs]: https://github.com/nothings/single_file_libs/blob/master/README.md
-[codacy-badge]: https://app.codacy.com/project/badge/Grade/2796b969c1b54321a02ad08affec0800
-[codacy-link]: https://www.codacy.com/gh/CLIUtils/CLI11/dashboard?utm_source=github.com&utm_medium=referral&utm_content=CLIUtils/CLI11&utm_campaign=Badge_Grade
+[single file libs]:
+  https://github.com/nothings/single_file_libs/blob/master/README.md
+[codacy-badge]:
+  https://app.codacy.com/project/badge/Grade/2796b969c1b54321a02ad08affec0800
+[codacy-link]:
+  https://www.codacy.com/gh/CLIUtils/CLI11/dashboard?utm_source=github.com&utm_medium=referral&utm_content=CLIUtils/CLI11&utm_campaign=Badge_Grade
 [hunter]: https://docs.hunter.sh/en/latest/packages/pkg/CLI11.html
 [standard readme style]: https://github.com/RichardLitt/standard-readme
 [argparse]: https://github.com/p-ranav/argparse
@@ -21,7 +21,11 @@ variables:
 jobs:
   - job: ClangTidy
     variables:
-      CXX_FLAGS: "-Werror -Wcast-align -Wfloat-equal -Wimplicit-atomic-properties -Wmissing-declarations -Woverlength-strings -Wshadow -Wstrict-selector-match -Wundeclared-selector -Wunreachable-code -std=c++11"
+      CXX_FLAGS: >
+        -Werror -Wcast-align -Wfloat-equal -Wimplicit-atomic-properties
+        -Wmissing-declarations -Woverlength-strings -Wshadow
+        -Wstrict-selector-match -Wundeclared-selector -Wunreachable-code
+        -std=c++11
       cli11.options: -DCLI11_CLANG_TIDY=ON -DCLI11_CLANG_TIDY_OPTIONS="-fix"
       cli11.std: 11
       cli11.single: OFF
 # CLI11: An introduction
  
-This gitbook is designed to provide an introduction to using the CLI11 library to write your own command line programs. The library is designed to be clean, intuitive, but powerful. There are no requirements beyond C++11 support (and even `<regex>` support not required). It works on Mac, Linux, and Windows, and has 100% test coverage on all three systems. You can simply drop in a single header file (`CLI11.hpp` available in [releases][]) to use CLI11 in your own application. Other ways to integrate it into a build system are listed in the [README][].
-
-The library was inspired the Python libraries [Plumbum][] and [Click][], and incorporates many of their user friendly features. The library is extensively documented, with a [friendly introduction][readme], this tutorial book, and more technical [API docs][].
-
-> Feel free to contribute to [this documentation here][cli11tutorial] if something can be improved!
-
-The syntax is simple and scales from a basic application to a massive physics analysis with multiple models and many parameters and switches. For example, this is a simple program that has an optional parameter that defaults to 0:
+This gitbook is designed to provide an introduction to using the CLI11 library
+to write your own command line programs. The library is designed to be clean,
+intuitive, but powerful. There are no requirements beyond C++11 support (and
+even `<regex>` support not required). It works on Mac, Linux, and Windows, and
+has 100% test coverage on all three systems. You can simply drop in a single
+header file (`CLI11.hpp` available in [releases][]) to use CLI11 in your own
+application. Other ways to integrate it into a build system are listed in the
+[README][].
+
+The library was inspired the Python libraries [Plumbum][] and [Click][], and
+incorporates many of their user friendly features. The library is extensively
+documented, with a [friendly introduction][readme], this tutorial book, and more
+technical [API docs][].
+
+> Feel free to contribute to [this documentation here][cli11tutorial] if
+> something can be improved!
+
+The syntax is simple and scales from a basic application to a massive physics
+analysis with multiple models and many parameters and switches. For example,
+this is a simple program that has an optional parameter that defaults to 0:
  
 ```term
 gitbook $ ./a.out
@@ -24,13 +37,16 @@ Options:
   -p INT                      Parameter
 ```
  
-Like any good command line application, help is provided. This program can be implemented in 10 lines:
+Like any good command line application, help is provided. This program can be
+implemented in 10 lines:
  
 [include](code/intro.cpp)
  
 [Source code](https://github.com/CLIUtils/CLI11/blob/main/book/code/intro.cpp)
  
-Unlike some other libraries, this is enough to exit correctly and cleanly if help is requested or if incorrect arguments are passed. You can try this example out for yourself. To compile with GCC:
+Unlike some other libraries, this is enough to exit correctly and cleanly if
+help is requested or if incorrect arguments are passed. You can try this example
+out for yourself. To compile with GCC:
  
 ```term
 gitbook:examples $ c++ -std=c++11 intro.cpp
@@ -45,13 +61,26 @@ app.add_option(&quot;-f,--file&quot;, file, &quot;Require an existing file&quot;)
   ->check(CLI::ExistingFile);
 ```
  
-You can use any valid type; the above example could have used a `boost::file_system` file instead of a `std::string`. The value is a real value and does not require any special lookups to access. You do not have to risk typos by repeating the values after parsing like some libraries require. The library also handles positional arguments, flags, fixed or unlimited repeating options, interdependent options, flags, custom validators, help groups, and more.
-
-You can use subcommands, as well. Subcommands support callback lambda functions when parsed, or they can be checked later. You can infinitely nest subcommands, and each is a full `App` instance, supporting everything listed above.
-
-Reading/producing `.ini` files for configuration is also supported, as is using environment variables as input. The base `App` can be subclassed and customized for use in a toolkit (like [GooFit][]). All the standard shell idioms, like `--`, work as well.
-
-CLI11 was developed at the [University of Cincinnati][] in support of the [GooFit][] library under [NSF Award 1414736][nsf 1414736]. It was featured in a [DIANA/HEP][] meeting at CERN. Please give it a try! Feedback is always welcome.
+You can use any valid type; the above example could have used a
+`boost::file_system` file instead of a `std::string`. The value is a real value
+and does not require any special lookups to access. You do not have to risk
+typos by repeating the values after parsing like some libraries require. The
+library also handles positional arguments, flags, fixed or unlimited repeating
+options, interdependent options, flags, custom validators, help groups, and
+more.
+
+You can use subcommands, as well. Subcommands support callback lambda functions
+when parsed, or they can be checked later. You can infinitely nest subcommands,
+and each is a full `App` instance, supporting everything listed above.
+
+Reading/producing `.ini` files for configuration is also supported, as is using
+environment variables as input. The base `App` can be subclassed and customized
+for use in a toolkit (like [GooFit][]). All the standard shell idioms, like
+`--`, work as well.
+
+CLI11 was developed at the [University of Cincinnati][] in support of the
+[GooFit][] library under [NSF Award 1414736][nsf 1414736]. It was featured in a
+[DIANA/HEP][] meeting at CERN. Please give it a try! Feedback is always welcome.
  
 [goofit]: https://github.com/GooFit/GooFit
 [diana/hep]: https://diana-hep.org
@@ -9,12 +9,15 @@ std::string opt;
 app.add_option("--my_option", opt)->envname("MY_OPTION");
 ```
  
-If not given on the command line, the environment variable will be checked and read from if it exists. All the standard tools, like default and required, work as expected.
-If passed on the command line, this will ignore the environment variable.
+If not given on the command line, the environment variable will be checked and
+read from if it exists. All the standard tools, like default and required, work
+as expected. If passed on the command line, this will ignore the environment
+variable.
  
 ## Needs/excludes
  
-You can set a network of requirements. For example, if flag a needs flag b but cannot be given with flag c, that would be:
+You can set a network of requirements. For example, if flag a needs flag b but
+cannot be given with flag c, that would be:
  
 ```cpp
 auto a = app.add_flag("-a");
@@ -25,11 +28,14 @@ a-&gt;needs(b);
 a->excludes(c);
 ```
  
-CLI11 will make sure your network of requirements makes sense, and will throw an error immediately if it does not.
+CLI11 will make sure your network of requirements makes sense, and will throw an
+error immediately if it does not.
  
 ## Custom option callbacks
  
-You can make a completely generic option with a custom callback. For example, if you wanted to add a complex number (already exists, so please don't actually do this):
+You can make a completely generic option with a custom callback. For example, if
+you wanted to add a complex number (already exists, so please don't actually do
+this):
  
 ```cpp
 CLI::Option *
@@ -62,7 +68,13 @@ add_option(app, &quot;-c,--complex&quot;, comp);
  
 ## Custom converters
  
-You can add your own converters to allow CLI11 to accept more option types in the standard calls. These can only be used for "single" size options (so complex, vector, etc. are a separate topic). If you set up a custom `istringstream& operator <<` overload before include CLI11, you can support different conversions. If you place this in the CLI namespace, you can even keep this from affecting the rest of your code. Here's how you could add `boost::optional` for a compiler that does not have `__has_include`:
+You can add your own converters to allow CLI11 to accept more option types in
+the standard calls. These can only be used for "single" size options (so
+complex, vector, etc. are a separate topic). If you set up a custom
+`istringstream& operator <<` overload before include CLI11, you can support
+different conversions. If you place this in the CLI namespace, you can even keep
+this from affecting the rest of your code. Here's how you could add
+`boost::optional` for a compiler that does not have `__has_include`:
  
 ```cpp
 // CLI11 already does this if __has_include is defined
@@ -87,7 +99,10 @@ template &lt;typename T&gt; std::istringstream &amp;operator&gt;&gt;(std::istringstream &amp;in, boo
 #include <CLI11.hpp>
 ```
  
-This is an example of how to use the system only; if you are just looking for a way to activate `boost::optional` support on older compilers, you should define `CLI11_BOOST_OPTIONAL` before including a CLI11 file, you'll get the `boost::optional` support.
+This is an example of how to use the system only; if you are just looking for a
+way to activate `boost::optional` support on older compilers, you should define
+`CLI11_BOOST_OPTIONAL` before including a CLI11 file, you'll get the
+`boost::optional` support.
  
 ## Custom converters and type names: std::chrono example
  
 # Making a git clone
  
-Let's try our hand at a little `git` clone, called `geet`. It will just print it's intent, rather than running actual code, since it's just a demonstration. Let's start by adding an app and requiring 1 subcommand to run:
+Let's try our hand at a little `git` clone, called `geet`. It will just print
+it's intent, rather than running actual code, since it's just a demonstration.
+Let's start by adding an app and requiring 1 subcommand to run:
  
 [include:"Intro"](../code/geet.cpp)
  
@@ -12,7 +14,8 @@ Now, let&#39;s add `commit`:
  
 [include:"Commit"](../code/geet.cpp)
  
-All that's need now is the parse call. We'll print a little message after the code runs, and then return:
+All that's need now is the parse call. We'll print a little message after the
+code runs, and then return:
  
 [include:"Parse"](../code/geet.cpp)
  
@@ -28,4 +31,9 @@ You&#39;ll see it behaves pretty much like `git`.
  
 ## Multi-file App parse code
  
-This example could be made much nicer if it was split into files, one per subcommand. If you simply use shared pointers instead of raw values in the lambda capture, you can tie the lifetime to the lambda function lifetime. CLI11 has a [multifile example](https://github.com/CLIUtils/CLI11/tree/main/examples/subcom_in_files) in its example folder.
+This example could be made much nicer if it was split into files, one per
+subcommand. If you simply use shared pointers instead of raw values in the
+lambda capture, you can tie the lifetime to the lambda function lifetime. CLI11
+has a
+[multifile example](https://github.com/CLIUtils/CLI11/tree/main/examples/subcom_in_files)
+in its example folder.
@@ -4,17 +4,30 @@ The simplest CLI11 program looks like this:
  
 [include](../code/simplest.cpp)
  
-The first line includes the library; this explicitly uses the single file edition (see [Selecting an edition](/chapters/installation)).
-
-After entering the main function, you'll see that a `CLI::App` object is created. This is the basis for all interactions with the library. You could optionally provide a description for your app here.
-
-A normal CLI11 application would define some flags and options next. This is a simplest possible example, so we'll go on.
-
-The macro `CLI11_PARSE` just runs five simple lines. This internally runs `app.parse(argc, argv)`, which takes the command line info from C++ and parses it. If there is an error, it throws a `ParseError`; if you catch it, you can use `app.exit` with the error as an argument to print a nice message and produce the correct return code for your application.
-
-If you just use `app.parse` directly, your application will still work, but the stack will not be correctly unwound since you have an uncaught exception, and the command line output will be cluttered, especially for help.
-
-For this (and most of the examples in this book) we will assume that we have the `CLI11.hpp` file in the current directory and that we are creating an output executable `a.out` on a macOS or Linux system. The commands to compile and test this example would be:
+The first line includes the library; this explicitly uses the single file
+edition (see [Selecting an edition](/chapters/installation)).
+
+After entering the main function, you'll see that a `CLI::App` object is
+created. This is the basis for all interactions with the library. You could
+optionally provide a description for your app here.
+
+A normal CLI11 application would define some flags and options next. This is a
+simplest possible example, so we'll go on.
+
+The macro `CLI11_PARSE` just runs five simple lines. This internally runs
+`app.parse(argc, argv)`, which takes the command line info from C++ and parses
+it. If there is an error, it throws a `ParseError`; if you catch it, you can use
+`app.exit` with the error as an argument to print a nice message and produce the
+correct return code for your application.
+
+If you just use `app.parse` directly, your application will still work, but the
+stack will not be correctly unwound since you have an uncaught exception, and
+the command line output will be cluttered, especially for help.
+
+For this (and most of the examples in this book) we will assume that we have the
+`CLI11.hpp` file in the current directory and that we are creating an output
+executable `a.out` on a macOS or Linux system. The commands to compile and test
+this example would be:
  
 ```term
 gitbook:examples $ g++ -std=c++11 simplest.cpp
@@ -2,17 +2,25 @@
  
 ## Reading a configure file
  
-You can tell your app to allow configure files with `set_config("--config")`. There are arguments: the first is the option name. If empty, it will clear the config flag. The second item is the default file name. If that is specified, the config will try to read that file. The third item is the help string, with a reasonable default, and the final argument is a boolean (default: false) that indicates that the configuration file is required and an error will be thrown if the file is not found and this is set to true.
+You can tell your app to allow configure files with `set_config("--config")`.
+There are arguments: the first is the option name. If empty, it will clear the
+config flag. The second item is the default file name. If that is specified, the
+config will try to read that file. The third item is the help string, with a
+reasonable default, and the final argument is a boolean (default: false) that
+indicates that the configuration file is required and an error will be thrown if
+the file is not found and this is set to true.
  
 ### Adding a default path
  
-if it is desired that config files be searched for a in a default path the `CLI::FileOnDefaultPath` transform can be used.
+if it is desired that config files be searched for a in a default path the
+`CLI::FileOnDefaultPath` transform can be used.
  
 ```cpp
 app.set_config("--config")->transform(CLI::FileOnDefaultPath("/default_path/"));
 ```
  
-This will allow specified files to either exist as given or on a specified default path.
+This will allow specified files to either exist as given or on a specified
+default path.
  
 ```cpp
 app.set_config("--config")
@@ -20,7 +28,10 @@ app.set_config(&quot;--config&quot;)
     ->transform(CLI::FileOnDefaultPath("/default_path2/",false));
 ```
  
-Multiple default paths can be specified through this mechanism. The last transform given is executed first so the error return must be disabled so it can be chained to the first. The same effect can be achieved though the or(`|`) operation with validators
+Multiple default paths can be specified through this mechanism. The last
+transform given is executed first so the error return must be disabled so it can
+be chained to the first. The same effect can be achieved though the or(`|`)
+operation with validators
  
 ```cpp
 app.set_config("--config")
@@ -29,32 +40,39 @@ app.set_config(&quot;--config&quot;)
  
 ### Extra fields
  
-Sometimes configuration files are used for multiple purposes so CLI11 allows options on how to deal with extra fields
+Sometimes configuration files are used for multiple purposes so CLI11 allows
+options on how to deal with extra fields
  
 ```cpp
 app.allow_config_extras(true);
 ```
  
-will allow capture the extras in the extras field of the app. (NOTE: This also sets the `allow_extras` in the app to true)
+will allow capture the extras in the extras field of the app. (NOTE: This also
+sets the `allow_extras` in the app to true)
  
 ```cpp
 app.allow_config_extras(false);
 ```
  
-will generate an error if there are any extra fields
-for slightly finer control there is a scoped enumeration of the modes or
+will generate an error if there are any extra fields for slightly finer control
+there is a scoped enumeration of the modes or
  
 ```cpp
 app.allow_config_extras(CLI::config_extras_mode::ignore);
 ```
  
-will completely ignore extra parameters in the config file. This mode is the default.
+will completely ignore extra parameters in the config file. This mode is the
+default.
  
 ```cpp
 app.allow_config_extras(CLI::config_extras_mode::capture);
 ```
  
-will store the unrecognized options in the app extras fields. This option is the closest equivalent to `app.allow_config_extras(true);` with the exception that it does not also set the `allow_extras` flag so using this option without also setting `allow_extras(true)` will generate an error which may or may not be the desired behavior.
+will store the unrecognized options in the app extras fields. This option is the
+closest equivalent to `app.allow_config_extras(true);` with the exception that
+it does not also set the `allow_extras` flag so using this option without also
+setting `allow_extras(true)` will generate an error which may or may not be the
+desired behavior.
  
 ```cpp
 app.allow_config_extras(CLI::config_extras_mode::error);
@@ -66,17 +84,20 @@ is equivalent to `app.allow_config_extras(false);`
 app.allow_config_extras(CLI::config_extras_mode::ignore_all);
 ```
  
-will completely ignore any mismatches, extras, or other issues with the config file
+will completely ignore any mismatches, extras, or other issues with the config
+file
  
 ### Getting the used configuration file name
  
 If it is needed to get the configuration file name used this can be obtained via
 `app.get_config_ptr()->as<std::string>()` or
-`app["--config"]->as<std::string>()` assuming `--config` was the configuration option name.
+`app["--config"]->as<std::string>()` assuming `--config` was the configuration
+option name.
  
 ## Configure file format
  
-Here is an example configuration file, in [TOML](https://github.com/toml-lang/toml) format:
+Here is an example configuration file, in
+[TOML](https://github.com/toml-lang/toml) format:
  
 ```ini
 # Comments are supported, using a #
@@ -93,7 +114,15 @@ in_subcommand = Wow
 subcommand = true # could also be give as sub.subcommand=true
 ```
  
-Spaces before and after the name and argument are ignored. Multiple arguments are separated by spaces. One set of quotes will be removed, preserving spaces (the same way the command line works). Boolean options can be `true`, `on`, `1`, `y`, `t`, `+`, `yes`, `enable`; or `false`, `off`, `0`, `no`, `n`, `f`, `-`, `disable`, (case insensitive). Sections (and `.` separated names) are treated as subcommands (note: this does not necessarily mean that subcommand was passed, it just sets the "defaults". If a subcommand is set to `configurable` then passing the subcommand using `[sub]` in a configuration file will trigger the subcommand.)
+Spaces before and after the name and argument are ignored. Multiple arguments
+are separated by spaces. One set of quotes will be removed, preserving spaces
+(the same way the command line works). Boolean options can be `true`, `on`, `1`,
+`y`, `t`, `+`, `yes`, `enable`; or `false`, `off`, `0`, `no`, `n`, `f`, `-`,
+`disable`, (case insensitive). Sections (and `.` separated names) are treated as
+subcommands (note: this does not necessarily mean that subcommand was passed, it
+just sets the "defaults". If a subcommand is set to `configurable` then passing
+the subcommand using `[sub]` in a configuration file will trigger the
+subcommand.)
  
 CLI11 also supports configuration file in INI format.
  
@@ -111,7 +140,9 @@ in_subcommand = Wow
 sub.subcommand = true
 ```
  
-The main differences are in vector notation and comment character. Note: CLI11 is not a full TOML parser as it just reads values as strings. It is possible (but not recommended) to mix notation.
+The main differences are in vector notation and comment character. Note: CLI11
+is not a full TOML parser as it just reads values as strings. It is possible
+(but not recommended) to mix notation.
  
 ## Multiple configuration files
  
@@ -121,11 +152,15 @@ If it is desired that multiple configuration be allowed. Use
 app.set_config("--config")->expected(1, X);
 ```
  
-Where X is some positive integer and will allow up to `X` configuration files to be specified by separate `--config` arguments.
+Where X is some positive integer and will allow up to `X` configuration files to
+be specified by separate `--config` arguments.
  
 ## Writing out a configure file
  
-To print a configuration file from the passed arguments, use `.config_to_str(default_also=false, write_description=false)`, where `default_also` will also show any defaulted arguments, and `write_description` will include option descriptions and the App description
+To print a configuration file from the passed arguments, use
+`.config_to_str(default_also=false, write_description=false)`, where
+`default_also` will also show any defaulted arguments, and `write_description`
+will include option descriptions and the App description
  
 ```cpp
  CLI::App app;
@@ -136,7 +171,8 @@ To print a configuration file from the passed arguments, use `.config_to_str(def
  std::cout<<app.config_to_str(true,true);
 ```
  
-if a prefix is needed to print before the options, for example to print a config for just a subcommand, the config formatter can be obtained directly.
+if a prefix is needed to print before the options, for example to print a config
+for just a subcommand, the config formatter can be obtained directly.
  
 ```cpp
   auto fmtr=app.get_config_formatter();
@@ -147,7 +183,11 @@ if a prefix is needed to print before the options, for example to print a config
  
 ### Customization of configure file output
  
-The default config parser/generator has some customization points that allow variations on the TOML format. The default formatter has a base configuration that matches the TOML format. It defines 5 characters that define how different aspects of the configuration are handled. You must use `get_config_formatter_base()` to have access to these fields
+The default config parser/generator has some customization points that allow
+variations on the TOML format. The default formatter has a base configuration
+that matches the TOML format. It defines 5 characters that define how different
+aspects of the configuration are handled. You must use
+`get_config_formatter_base()` to have access to these fields
  
 ```cpp
 /// the character used for comments
@@ -176,41 +216,62 @@ std::string configSection;
  
 These can be modified via setter functions
  
-- `ConfigBase *comment(char cchar)`: Specify the character to start a comment block
-- `ConfigBase *arrayBounds(char aStart, char aEnd)`: Specify the start and end characters for an array
-- `ConfigBase *arrayDelimiter(char aSep)`: Specify the delimiter character for an array
-- `ConfigBase *valueSeparator(char vSep)`: Specify the delimiter between a name and value
-- `ConfigBase *quoteCharacter(char qString, char qChar)` :specify the characters to use around strings and single characters
-- `ConfigBase *maxLayers(uint8_t layers)` : specify the maximum number of parent layers to process. This is useful to limit processing for larger config files
-- `ConfigBase *parentSeparator(char sep)` : specify the character to separate parent layers from options
-- `ConfigBase *section(const std::string &sectionName)` : specify the section name to use to get the option values, only this section will be processed
-- `ConfigBase *index(uint16_t sectionIndex)` : specify an index section to use for processing if multiple TOML sections of the same name are present `[[section]]`
-
-For example, to specify reading a configure file that used `:` to separate name and values:
+- `ConfigBase *comment(char cchar)`: Specify the character to start a comment
+  block
+- `ConfigBase *arrayBounds(char aStart, char aEnd)`: Specify the start and end
+  characters for an array
+- `ConfigBase *arrayDelimiter(char aSep)`: Specify the delimiter character for
+  an array
+- `ConfigBase *valueSeparator(char vSep)`: Specify the delimiter between a name
+  and value
+- `ConfigBase *quoteCharacter(char qString, char qChar)` :specify the characters
+  to use around strings and single characters
+- `ConfigBase *maxLayers(uint8_t layers)` : specify the maximum number of parent
+  layers to process. This is useful to limit processing for larger config files
+- `ConfigBase *parentSeparator(char sep)` : specify the character to separate
+  parent layers from options
+- `ConfigBase *section(const std::string &sectionName)` : specify the section
+  name to use to get the option values, only this section will be processed
+- `ConfigBase *index(uint16_t sectionIndex)` : specify an index section to use
+  for processing if multiple TOML sections of the same name are present
+  `[[section]]`
+
+For example, to specify reading a configure file that used `:` to separate name
+and values:
  
 ```cpp
 auto config_base=app.get_config_formatter_base();
 config_base->valueSeparator(':');
 ```
  
-The default configuration file will read INI files, but will write out files in the TOML format. To specify outputting INI formatted files use
+The default configuration file will read INI files, but will write out files in
+the TOML format. To specify outputting INI formatted files use
  
 ```cpp
 app.config_formatter(std::make_shared<CLI::ConfigINI>());
 ```
  
-which makes use of a predefined modification of the ConfigBase class which TOML also uses. If a custom formatter is used that is not inheriting from the from ConfigBase class `get_config_formatter_base() will return a nullptr if RTTI is on (usually the default), or garbage if RTTI is off, so some care must be exercised in its use with custom configurations.
+which makes use of a predefined modification of the ConfigBase class which TOML
+also uses. If a custom formatter is used that is not inheriting from the from
+ConfigBase class `get_config_formatter_base() will return a nullptr if RTTI is
+on (usually the default), or garbage if RTTI is off, so some care must be
+exercised in its use with custom configurations.
  
 ## Custom formats
  
-You can invent a custom format and set that instead of the default INI formatter. You need to inherit from `CLI::Config` and implement the following two functions:
+You can invent a custom format and set that instead of the default INI
+formatter. You need to inherit from `CLI::Config` and implement the following
+two functions:
  
 ```cpp
 std::string to_config(const CLI::App *app, bool default_also, bool, std::string) const;
 std::vector<CLI::ConfigItem> from_config(std::istream &input) const;
 ```
  
-The `CLI::ConfigItem`s that you return are simple structures with a name, a vector of parents, and a vector of results. A optionally customizable `to_flag` method on the formatter lets you change what happens when a ConfigItem turns into a flag.
+The `CLI::ConfigItem`s that you return are simple structures with a name, a
+vector of parents, and a vector of results. A optionally customizable `to_flag`
+method on the formatter lets you change what happens when a ConfigItem turns
+into a flag.
  
 Finally, set your new class as new config formatter:
  
@@ -218,7 +279,9 @@ Finally, set your new class as new config formatter:
 app.config_formatter(std::make_shared<NewConfig>());
 ```
  
-See [`examples/json.cpp`](https://github.com/CLIUtils/CLI11/blob/main/examples/json.cpp) for a complete JSON config example.
+See
+[`examples/json.cpp`](https://github.com/CLIUtils/CLI11/blob/main/examples/json.cpp)
+for a complete JSON config example.
  
 ### Trivial JSON configuration example
  
@@ -236,21 +299,40 @@ The parser can handle these structures with only a minor tweak
 app.get_config_formatter_base()->valueSeparator(':');
 ```
  
-The open and close brackets must be on a separate line and the comma gets interpreted as an array separator but since no values are after the comma they get ignored as well. This will not support multiple layers or sections or any other moderately complex JSON, but can work if the input file is simple.
+The open and close brackets must be on a separate line and the comma gets
+interpreted as an array separator but since no values are after the comma they
+get ignored as well. This will not support multiple layers or sections or any
+other moderately complex JSON, but can work if the input file is simple.
  
 ## Triggering Subcommands
  
-Configuration files can be used to trigger subcommands if a subcommand is set to configure. By default configuration file just set the default values of a subcommand. But if the `configure()` option is set on a subcommand then the if the subcommand is utilized via a `[subname]` block in the configuration file it will act as if it were called from the command line. Subsubcommands can be triggered via `[subname.subsubname]`. Using the `[[subname]]` will be as if the subcommand were triggered multiple times from the command line. This functionality can allow the configuration file to act as a scripting file.
+Configuration files can be used to trigger subcommands if a subcommand is set to
+configure. By default configuration file just set the default values of a
+subcommand. But if the `configure()` option is set on a subcommand then the if
+the subcommand is utilized via a `[subname]` block in the configuration file it
+will act as if it were called from the command line. Subsubcommands can be
+triggered via `[subname.subsubname]`. Using the `[[subname]]` will be as if the
+subcommand were triggered multiple times from the command line. This
+functionality can allow the configuration file to act as a scripting file.
  
-For custom configuration files this behavior can be triggered by specifying the parent subcommands in the structure and `++` as the name to open a new subcommand scope and `--` to close it. These names trigger the different callbacks of configurable subcommands.
+For custom configuration files this behavior can be triggered by specifying the
+parent subcommands in the structure and `++` as the name to open a new
+subcommand scope and `--` to close it. These names trigger the different
+callbacks of configurable subcommands.
  
 ## Stream parsing
  
-In addition to the regular parse functions a `parse_from_stream(std::istream &input)` is available to directly parse a stream operator. For example to process some arguments in an already open file stream. The stream is fed directly in the config parser so bypasses the normal command line parsing.
+In addition to the regular parse functions a
+`parse_from_stream(std::istream &input)` is available to directly parse a stream
+operator. For example to process some arguments in an already open file stream.
+The stream is fed directly in the config parser so bypasses the normal command
+line parsing.
  
 ## Implementation Notes
  
-The config file input works with any form of the option given: Long, short, positional, or the environment variable name. When generating a config file it will create an option name in following priority.
+The config file input works with any form of the option given: Long, short,
+positional, or the environment variable name. When generating a config file it
+will create an option name in following priority.
  
 1. First long name
 2. Positional name
 # Adding Flags
  
-The most basic addition to a command line program is a flag. This is simply something that does not take any arguments. Adding a flag in CLI11 is done in one of three ways.
+The most basic addition to a command line program is a flag. This is simply
+something that does not take any arguments. Adding a flag in CLI11 is done in
+one of three ways.
  
 ## Boolean flags
  
@@ -11,60 +13,93 @@ bool my_flag{false};
 app.add_flag("-f", my_flag, "Optional description");
 ```
  
-This will bind the flag `-f` to the boolean `my_flag`. After the parsing step, `my_flag` will be `false` if the flag was not found on the command line, or `true` if it was. By default, it will be allowed any number of times, but if you explicitly\[^1\] request `->take_last(false)`, it will only be allowed once; passing something like `./my_app -f -f` or `./my_app -ff` will throw a `ParseError` with a nice help description. A flag name may start with any character except ('-', ' ', '\n', and '!'). For long flags, after the first character all characters are allowed except ('=',':','{',' ', '\n'). Names are given as a comma separated string, with the dash or dashes. An flag can have as many names as you want, and afterward, using `count`, you can use any of the names, with dashes as needed.
+This will bind the flag `-f` to the boolean `my_flag`. After the parsing step,
+`my_flag` will be `false` if the flag was not found on the command line, or
+`true` if it was. By default, it will be allowed any number of times, but if you
+explicitly\[^1\] request `->take_last(false)`, it will only be allowed once;
+passing something like `./my_app -f -f` or `./my_app -ff` will throw a
+`ParseError` with a nice help description. A flag name may start with any
+character except ('-', ' ', '\n', and '!'). For long flags, after the first
+character all characters are allowed except ('=',':','{',' ', '\n'). Names are
+given as a comma separated string, with the dash or dashes. An flag can have as
+many names as you want, and afterward, using `count`, you can use any of the
+names, with dashes as needed.
  
 ## Integer flags
  
-If you want to allow multiple flags and count their value, simply use any integral variables instead of a bool:
+If you want to allow multiple flags and count their value, simply use any
+integral variables instead of a bool:
  
 ```cpp
 int my_flag{0};
 app.add_flag("-f", my_flag, "Optional description");
 ```
  
-After the parsing step, `my_flag` will contain the number of times this flag was found on the command line, including 0 if not found.
+After the parsing step, `my_flag` will contain the number of times this flag was
+found on the command line, including 0 if not found.
  
-This behavior can also be controlled manually via `->multi_option_policy(CLI::MultiOptionPolicy::Sum)` as of version 2.2.
+This behavior can also be controlled manually via
+`->multi_option_policy(CLI::MultiOptionPolicy::Sum)` as of version 2.2.
  
 ## Arbitrary type flags
  
-CLI11 allows the type of the variable to assign to in the `add_flag` function to be any supported type. This is particularly useful in combination with specifying default values for flags. The allowed types include bool, int, float, vector, enum, or string-like.
+CLI11 allows the type of the variable to assign to in the `add_flag` function to
+be any supported type. This is particularly useful in combination with
+specifying default values for flags. The allowed types include bool, int, float,
+vector, enum, or string-like.
  
 ### Default Flag Values
  
-Flag options specified through the `add_flag*` functions allow a syntax for the option names to default particular options to a false value or any other value if some flags are passed. For example:
+Flag options specified through the `add_flag*` functions allow a syntax for the
+option names to default particular options to a false value or any other value
+if some flags are passed. For example:
  
 ```cpp
 app.add_flag("--flag,!--no-flag",result,"help for flag");
 ```
  
-specifies that if `--flag` is passed on the command line result will be true or contain a value of 1. If `--no-flag` is
-passed `result` will contain false or -1 if `result` is a signed integer type, or 0 if it is an unsigned type. An
-alternative form of the syntax is more explicit: `"--flag,--no-flag{false}"`; this is equivalent to the previous
-example. This also works for short form options `"-f,!-n"` or `"-f,-n{false}"`. If `variable_to_bind_to` is anything but an integer value the
-default behavior is to take the last value given, while if `variable_to_bind_to` is an integer type the behavior will be to sum
-all the given arguments and return the result. This can be modified if needed by changing the `multi_option_policy` on each flag (this is not inherited).
-The default value can be any value. For example if you wished to define a numerical flag:
+specifies that if `--flag` is passed on the command line result will be true or
+contain a value of 1. If `--no-flag` is passed `result` will contain false or -1
+if `result` is a signed integer type, or 0 if it is an unsigned type. An
+alternative form of the syntax is more explicit: `"--flag,--no-flag{false}"`;
+this is equivalent to the previous example. This also works for short form
+options `"-f,!-n"` or `"-f,-n{false}"`. If `variable_to_bind_to` is anything but
+an integer value the default behavior is to take the last value given, while if
+`variable_to_bind_to` is an integer type the behavior will be to sum all the
+given arguments and return the result. This can be modified if needed by
+changing the `multi_option_policy` on each flag (this is not inherited). The
+default value can be any value. For example if you wished to define a numerical
+flag:
  
 ```cpp
 app.add_flag("-1{1},-2{2},-3{3}",result,"numerical flag")
 ```
  
-using any of those flags on the command line will result in the specified number in the output. Similar things can be done for string values, and enumerations, as long as the default value can be converted to the given type.
+using any of those flags on the command line will result in the specified number
+in the output. Similar things can be done for string values, and enumerations,
+as long as the default value can be converted to the given type.
  
 ## Pure flags
  
-Every command that starts with `add_`, such as the flag commands, return a pointer to the internally stored `CLI::Option` that describes your addition. If you prefer, you can capture this pointer and use it, and that allows you to skip adding a variable to bind to entirely:
+Every command that starts with `add_`, such as the flag commands, return a
+pointer to the internally stored `CLI::Option` that describes your addition. If
+you prefer, you can capture this pointer and use it, and that allows you to skip
+adding a variable to bind to entirely:
  
 ```cpp
 CLI::Option* my_flag = app.add_flag("-f", "Optional description");
 ```
  
-After parsing, you can use `my_flag->count()` to count the number of times this was found. You can also directly use the value (`*my_flag`) as a bool. `CLI::Option` will be discussed in more detail later.
+After parsing, you can use `my_flag->count()` to count the number of times this
+was found. You can also directly use the value (`*my_flag`) as a bool.
+`CLI::Option` will be discussed in more detail later.
  
 ## Callback flags
  
-If you want to define a callback that runs when you make a flag, you can use `add_flag_function` (C++11 or newer) or `add_flag` (C++14 or newer only) to add a callback function. The function should have the signature `void(std::size_t)`. This could be useful for a version printout, etc.
+If you want to define a callback that runs when you make a flag, you can use
+`add_flag_function` (C++11 or newer) or `add_flag` (C++14 or newer only) to add
+a callback function. The function should have the signature `void(std::size_t)`.
+This could be useful for a version printout, etc.
  
 ```cpp
 auto callback = [](int count){std::cout << "This was called " << count << " times";};
@@ -73,9 +108,15 @@ app.add_flag_function(&quot;-c&quot;, callback, &quot;Optional description&quot;);
  
 ## Aliases
  
-The name string, the first item of every `add_` method, can contain as many short and long names as you want, separated by commas. For example, `"-a,--alpha,-b,--beta"` would allow any of those to be recognized on the command line. If you use the same name twice, or if you use the same name in multiple flags, CLI11 will immediately throw a `CLI::ConstructionError` describing your problem (it will not wait until the parsing step).
+The name string, the first item of every `add_` method, can contain as many
+short and long names as you want, separated by commas. For example,
+`"-a,--alpha,-b,--beta"` would allow any of those to be recognized on the
+command line. If you use the same name twice, or if you use the same name in
+multiple flags, CLI11 will immediately throw a `CLI::ConstructionError`
+describing your problem (it will not wait until the parsing step).
  
-If you want to make an option case insensitive, you can use the `->ignore_case()` method on the `CLI::Option` to do that. For example,
+If you want to make an option case insensitive, you can use the
+`->ignore_case()` method on the `CLI::Option` to do that. For example,
  
 ```cpp
 bool flag{false};
@@ -122,4 +163,5 @@ Flag int: 3
 Flag plain: 1
 ```
  
-\[^1\]: It will not inherit this from the parent defaults, since this is often useful even if you don't want all options to allow multiple passed options.
+\[^1\]: It will not inherit this from the parent defaults, since this is often
+useful even if you don't want all options to allow multiple passed options.
 # Formatting help output
  
-{% hint style='info' %}
-New in CLI11 1.6
-{% endhint %}
+{% hint style='info' %} New in CLI11 1.6 {% endhint %}
  
 ## Customizing an existing formatter
  
-In CLI11, you can control the output of the help printout in full or in part. The default formatter was written in such a way as to be customizable. You can use `app.get_formatter()` to get the current formatter. The formatter you set will be inherited by subcommands that are created after you set the formatter.
+In CLI11, you can control the output of the help printout in full or in part.
+The default formatter was written in such a way as to be customizable. You can
+use `app.get_formatter()` to get the current formatter. The formatter you set
+will be inherited by subcommands that are created after you set the formatter.
  
 There are several configuration options that you can set:
  
@@ -15,7 +16,9 @@ There are several configuration options that you can set:
 | `column_width(width)` | The width of the columns         | Both         |
 | `label(key, value)`   | Set a label to a different value | Both         |
  
-Labels will map the built in names and type names from key to value if present. For example, if you wanted to change the width of the columns to 40 and the `REQUIRED` label from `(REQUIRED)` to `(MUST HAVE)`:
+Labels will map the built in names and type names from key to value if present.
+For example, if you wanted to change the width of the columns to 40 and the
+`REQUIRED` label from `(REQUIRED)` to `(MUST HAVE)`:
  
 ```cpp
 app.get_formatter()->column_width(40);
@@ -24,7 +27,11 @@ app.get_formatter()-&gt;label(&quot;REQUIRED&quot;, &quot;(MUST HAVE)&quot;);
  
 ## Subclassing
  
-You can further configure pieces of the code while still keeping most of the formatting intact by subclassing either formatter and replacing any of the methods with your own. The formatters use virtual functions most places, so you are free to add or change anything about them. For example, if you wanted to remove the info that shows up between the option name and the description:
+You can further configure pieces of the code while still keeping most of the
+formatting intact by subclassing either formatter and replacing any of the
+methods with your own. The formatters use virtual functions most places, so you
+are free to add or change anything about them. For example, if you wanted to
+remove the info that shows up between the option name and the description:
  
 ```cpp
 class MyFormatter : public CLI::Formatter {
@@ -34,11 +41,14 @@ class MyFormatter : public CLI::Formatter {
 app.formatter(std::make_shared<MyFormatter>());
 ```
  
-Look at the class definitions in `FormatterFwd.hpp` or the method definitions in `Formatter.hpp` to see what methods you have access to and how they are put together.
+Look at the class definitions in `FormatterFwd.hpp` or the method definitions in
+`Formatter.hpp` to see what methods you have access to and how they are put
+together.
  
 ## Anatomy of a help message
  
-This is a normal printout, with `<>` indicating the methods used to produce each line.
+This is a normal printout, with `<>` indicating the methods used to produce each
+line.
  
 ```text
 <make_description(app)>
@@ -55,9 +65,11 @@ This is a normal printout, with `&lt;&gt;` indicating the methods used to produce each
 <make_footer(app)>
 ```
  
-`make_usage` calls `make_option_usage(opt)` on all the positionals to build that part of the line. `make_subcommand` passes the subcommand as the app pointer.
+`make_usage` calls `make_option_usage(opt)` on all the positionals to build that
+part of the line. `make_subcommand` passes the subcommand as the app pointer.
  
-The `make_groups` print the group name then call `make_option(o)` on the options listed in that group. The normal printout for an option looks like this:
+The `make_groups` print the group name then call `make_option(o)` on the options
+listed in that group. The normal printout for an option looks like this:
  
 ```text
         make_option_opts(o)
@@ -69,5 +81,6 @@ make_option_name(o,p)        make_option_desc(o)
  
 Notes:
  
-- `*1`: This signature depends on whether the call is from a positional or optional.
+- `*1`: This signature depends on whether the call is from a positional or
+  optional.
 - `o` is opt pointer, `p` is true if positional.
@@ -6,7 +6,10 @@
 #include <CLI11.hpp>
 ```
  
-This example uses the single file edition of CLI11. You can download `CLI11.hpp` from the latest release and put it into the same folder as your source code, then compile this with C++ enabled. For a larger project, you can just put this in an include folder and you are set.
+This example uses the single file edition of CLI11. You can download `CLI11.hpp`
+from the latest release and put it into the same folder as your source code,
+then compile this with C++ enabled. For a larger project, you can just put this
+in an include folder and you are set.
  
 ## Full edition
  
@@ -14,27 +17,42 @@ This example uses the single file edition of CLI11. You can download `CLI11.hpp`
 #include <CLI/CLI.hpp>
 ```
  
-If you want to use CLI11 in its full form, you can also use the original multiple file edition. This has an extra utility (`Timer`), and is does not require that you use a release. The only change to your code would be the include shown above.
+If you want to use CLI11 in its full form, you can also use the original
+multiple file edition. This has an extra utility (`Timer`), and is does not
+require that you use a release. The only change to your code would be the
+include shown above.
  
 ### CMake support for the full edition
  
-If you use CMake 3.4+ for your project (highly recommended), CLI11 comes with a powerful CMakeLists.txt file that was designed to also be used with `add_subproject`. You can add the repository to your code (preferably as a git submodule), then add the following line to your project (assuming your folder is called CLI11):
+If you use CMake 3.4+ for your project (highly recommended), CLI11 comes with a
+powerful CMakeLists.txt file that was designed to also be used with
+`add_subproject`. You can add the repository to your code (preferably as a git
+submodule), then add the following line to your project (assuming your folder is
+called CLI11):
  
 ```cmake
 add_subdirectory(CLI11)
 ```
  
-Then, you will have a target `CLI11::CLI11` that you can link to with `target_link_libraries`. It will provide the include paths you need for the library. This is the way [GooFit](https://github.com/GooFit/GooFit) uses CLI11, for example.
+Then, you will have a target `CLI11::CLI11` that you can link to with
+`target_link_libraries`. It will provide the include paths you need for the
+library. This is the way [GooFit](https://github.com/GooFit/GooFit) uses CLI11,
+for example.
  
-You can also configure and optionally install CLI11, and CMake will create the necessary `lib/cmake/CLI11/CLI11Config.cmake` files, so `find_package(CLI11 CONFIG REQUIRED)` also works.
+You can also configure and optionally install CLI11, and CMake will create the
+necessary `lib/cmake/CLI11/CLI11Config.cmake` files, so
+`find_package(CLI11 CONFIG REQUIRED)` also works.
  
 If you use conan.io, CLI11 supports that too.
  
 ### Running tests on the full edition
  
-CLI11 has examples and tests that can be accessed using a CMake build on any platform. Simply build and run ctest to run the 200+ tests to ensure CLI11 works on your system.
+CLI11 has examples and tests that can be accessed using a CMake build on any
+platform. Simply build and run ctest to run the 200+ tests to ensure CLI11 works
+on your system.
  
-As an example of the build system, the following code will download and test CLI11 in a simple Alpine Linux docker container [^1]:
+As an example of the build system, the following code will download and test
+CLI11 in a simple Alpine Linux docker container [^1]:
  
 ```term
 gitbook:~ $ docker run -it alpine
@@ -78,7 +96,8 @@ Test project /CLI11/build
 Total Test time (real) =   0.34 sec
 ```
  
-For the curious, the CMake options and defaults are listed below. Most options default to off if CLI11 is used as a subdirectory in another project.
+For the curious, the CMake options and defaults are listed below. Most options
+default to off if CLI11 is used as a subdirectory in another project.
  
 | Option                        | Description                                                                                     |
 | ----------------------------- | ----------------------------------------------------------------------------------------------- |
@@ -89,4 +108,7 @@ For the curious, the CMake options and defaults are listed below. Most options d
 | `CLI11_CLANG_TIDY=OFF`        | Run `clang-tidy` on the examples and headers. Requires CMake 3.6+.                              |
 | `CLI11_CLANG_TIDY_OPTIONS=""` | Options to pass to `clang-tidy`, such as `-fix` (single threaded build only if applying fixes!) |
  
-[^1]: Docker is being used to create a pristine disposable environment; there is nothing special about this container. Alpine is being used because it is small, modern, and fast. Commands are similar on any other platform.
+[^1]:
+    Docker is being used to create a pristine disposable environment; there is
+    nothing special about this container. Alpine is being used because it is
+    small, modern, and fast. Commands are similar on any other platform.
@@ -2,7 +2,8 @@
  
 ## Callbacks
  
-The library was designed to bind to existing variables without requiring typed classes or inheritance. This is accomplished through lambda functions.
+The library was designed to bind to existing variables without requiring typed
+classes or inheritance. This is accomplished through lambda functions.
  
 This looks like:
  
@@ -14,30 +15,40 @@ Option* add_option(string name, T item) {
 }
 ```
  
-Obviously, you can't access `T` after the `add_` method is over, so it stores the string representation of the default value if it receives the special `true` value as the final argument (not shown above).
+Obviously, you can't access `T` after the `add_` method is over, so it stores
+the string representation of the default value if it receives the special `true`
+value as the final argument (not shown above).
  
 ## Parsing
  
 Parsing follows the following procedure:
  
-1. `_validate`: Make sure the defined options and subcommands are self consistent.
+1. `_validate`: Make sure the defined options and subcommands are self
+   consistent.
 2. `_parse`: Main parsing routine. See below.
 3. `_run_callback`: Run an App callback if present.
  
 The parsing phase is the most interesting:
  
-1. `_parse_single`: Run on each entry on the command line and fill the options/subcommands.
+1. `_parse_single`: Run on each entry on the command line and fill the
+   options/subcommands.
 2. `_process`: Run the procedure listed below.
-3. `_process_extra`: This throws an error if needed on extra arguments that didn't fit in the parse.
+3. `_process_extra`: This throws an error if needed on extra arguments that
+   didn't fit in the parse.
  
-The `_process` procedure runs the following steps; each step is recursive and completes all subcommands before moving to the next step (new in 1.7). This ensures that interactions between options and subcommand options is consistent.
+The `_process` procedure runs the following steps; each step is recursive and
+completes all subcommands before moving to the next step (new in 1.7). This
+ensures that interactions between options and subcommand options is consistent.
  
 1. `_process_ini`: This reads an INI file and fills/changes options as needed.
 2. `_process_env`: Look for environment variables.
-3. `_process_callbacks`: Run the callback functions - this fills out the variables.
+3. `_process_callbacks`: Run the callback functions - this fills out the
+   variables.
 4. `_process_help_flags`: Run help flags if present (and quit).
-5. `_process_requirements`: Make sure needs/excludes, required number of options present.
+5. `_process_requirements`: Make sure needs/excludes, required number of options
+   present.
  
 ## Exceptions
  
-The library immediately returns a C++ exception when it detects a problem, such as an incorrect construction or a malformed command line.
+The library immediately returns a C++ exception when it detects a problem, such
+as an incorrect construction or a malformed command line.
@@ -2,21 +2,29 @@
  
 ## Simple options
  
-The most versatile addition to a command line program is an option. This is like a flag, but it takes an argument. CLI11 handles all the details for many types of options for you, based on their type. To add an option:
+The most versatile addition to a command line program is an option. This is like
+a flag, but it takes an argument. CLI11 handles all the details for many types
+of options for you, based on their type. To add an option:
  
 ```cpp
 int int_option{0};
 app.add_option("-i", int_option, "Optional description");
 ```
  
-This will bind the option `-i` to the integer `int_option`. On the command line, a single value that can be converted to an integer will be expected. Non-integer results will fail. If that option is not given, CLI11 will not touch the initial value. This allows you to set up defaults by simply setting your value beforehand. If you want CLI11 to display your default value, you can add `->capture_default_str()` after the option.
+This will bind the option `-i` to the integer `int_option`. On the command line,
+a single value that can be converted to an integer will be expected. Non-integer
+results will fail. If that option is not given, CLI11 will not touch the initial
+value. This allows you to set up defaults by simply setting your value
+beforehand. If you want CLI11 to display your default value, you can add
+`->capture_default_str()` after the option.
  
 ```cpp
 int int_option{0};
 app.add_option("-i", int_option, "Optional description")->capture_default_str();
 ```
  
-You can use any C++ int-like type, not just `int`. CLI11 understands the following categories of types:
+You can use any C++ int-like type, not just `int`. CLI11 understands the
+following categories of types:
  
 | Type           | CLI11                                                                                                                                                                             |
 | -------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
@@ -31,35 +39,60 @@ You can use any C++ int-like type, not just `int`. CLI11 understands the followi
 | function       | A function that takes an array of strings and returns a string that describes the conversion failure or empty for success. May be the empty function. (`{}`)                      |
 | streamable     | any other type with a `<<` operator will also work                                                                                                                                |
  
-By default, CLI11 will assume that an option is optional, and one value is expected if you do not use a vector. You can change this on a specific option using option modifiers. An option name may start with any character except ('-', ' ', '\n', and '!'). For long options, after the first character all characters are allowed except ('=',':','{',' ', '\n'). Names are given as a comma separated string, with the dash or dashes. An option can have as many names as you want, and afterward, using `count`, you can use any of the names, with dashes as needed, to count the options. One of the names is allowed to be given without proceeding dash(es); if present the option is a positional option, and that name will be used on the help line for its positional form.
+By default, CLI11 will assume that an option is optional, and one value is
+expected if you do not use a vector. You can change this on a specific option
+using option modifiers. An option name may start with any character except ('-',
+' ', '\n', and '!'). For long options, after the first character all characters
+are allowed except ('=',':','{',' ', '\n'). Names are given as a comma separated
+string, with the dash or dashes. An option can have as many names as you want,
+and afterward, using `count`, you can use any of the names, with dashes as
+needed, to count the options. One of the names is allowed to be given without
+proceeding dash(es); if present the option is a positional option, and that name
+will be used on the help line for its positional form.
  
 ## Positional options and aliases
  
-When you give an option on the command line without a name, that is a positional option. Positional options are accepted in the same order they are defined. So, for example:
+When you give an option on the command line without a name, that is a positional
+option. Positional options are accepted in the same order they are defined. So,
+for example:
  
 ```term
 gitbook:examples $ ./a.out one --two three four
 ```
  
-The string `one` would have to be the first positional option. If `--two` is a flag, then the remaining two strings are positional. If `--two` is a one-argument option, then `four` is the second positional. If `--two` accepts two or more arguments, then there are no more positionals.
+The string `one` would have to be the first positional option. If `--two` is a
+flag, then the remaining two strings are positional. If `--two` is a
+one-argument option, then `four` is the second positional. If `--two` accepts
+two or more arguments, then there are no more positionals.
  
-To make a positional option, you simply give CLI11 one name that does not start with a dash. You can have as many (non-overlapping) names as you want for an option, but only one positional name. So the following name string is valid:
+To make a positional option, you simply give CLI11 one name that does not start
+with a dash. You can have as many (non-overlapping) names as you want for an
+option, but only one positional name. So the following name string is valid:
  
 ```cpp
 "-a,-b,--alpha,--beta,mypos"
 ```
  
-This would make two short option aliases, two long option alias, and the option would be also be accepted as a positional.
+This would make two short option aliases, two long option alias, and the option
+would be also be accepted as a positional.
  
 ## Containers of options
  
-If you use a vector or other container instead of a plain option, you can accept more than one value on the command line. By default, a container accepts as many options as possible, until the next value that could be a valid option name. You can specify a set number using an option modifier `->expected(N)`. (The default unlimited behavior on vectors is restored with `N=-1`) CLI11 does not differentiate between these two methods for unlimited acceptance options.
+If you use a vector or other container instead of a plain option, you can accept
+more than one value on the command line. By default, a container accepts as many
+options as possible, until the next value that could be a valid option name. You
+can specify a set number using an option modifier `->expected(N)`. (The default
+unlimited behavior on vectors is restored with `N=-1`) CLI11 does not
+differentiate between these two methods for unlimited acceptance options.
  
 | Separate names    | Combined names |
 | ----------------- | -------------- |
 | `--vec 1 --vec 2` | `--vec 1 2`    |
  
-It is also possible to specify a minimum and maximum number through `->expected(Min,Max)`. It is also possible to specify a min and max type size for the elements of the container. It most cases these values will be automatically determined but a user can manually restrict them.
+It is also possible to specify a minimum and maximum number through
+`->expected(Min,Max)`. It is also possible to specify a min and max type size
+for the elements of the container. It most cases these values will be
+automatically determined but a user can manually restrict them.
  
 An example of setting up a vector option:
  
@@ -68,13 +101,19 @@ std::vector&lt;int&gt; int_vec;
 app.add_option("--vec", int_vec, "My vector option");
 ```
  
-Vectors will be replaced by the parsed content if the option is given on the command line.
+Vectors will be replaced by the parsed content if the option is given on the
+command line.
  
-A definition of a container for purposes of CLI11 is a type with a `end()`, `insert(...)`, `clear()` and `value_type` definitions. This includes `vector`, `set`, `deque`, `list`, `forward_iist`, `map`, `unordered_map` and a few others from the standard library, and many other containers from the boost library.
+A definition of a container for purposes of CLI11 is a type with a `end()`,
+`insert(...)`, `clear()` and `value_type` definitions. This includes `vector`,
+`set`, `deque`, `list`, `forward_iist`, `map`, `unordered_map` and a few others
+from the standard library, and many other containers from the boost library.
  
 ### Empty containers
  
-By default a container will never return an empty container. If it is desired to allow an empty container to be returned, then the option must be modified with a 0 as the minimum expected value
+By default a container will never return an empty container. If it is desired to
+allow an empty container to be returned, then the option must be modified with a
+0 as the minimum expected value
  
 ```cpp
 std::vector<int> int_vec;
@@ -83,7 +122,8 @@ app.add_option(&quot;--vec&quot;, int_vec, &quot;Empty vector allowed&quot;)-&gt;expected(0,-1);
  
 An empty vector can than be specified on the command line as `--vec {}`
  
-To allow an empty vector from config file, the default must be set in addition to the above modification.
+To allow an empty vector from config file, the default must be set in addition
+to the above modification.
  
 ```cpp
 std::vector<int> int_vec;
@@ -113,13 +153,20 @@ std::vector&lt;std::vector&lt;int&gt;&gt; int_vec;
 app.add_option("--vec", int_vec, "My vector of vectors option");
 ```
  
-CLI11 inserts a separator sequence at the start of each argument call to separate the vectors. So unless the separators are injected as part of the command line each call of the option on the command line will result in a separate element of the outer vector. This can be manually controlled via `inject_separator(true|false)` but in nearly all cases this should be left to the defaults. To insert of a separator from the command line add a `%%` where the separation should occur.
+CLI11 inserts a separator sequence at the start of each argument call to
+separate the vectors. So unless the separators are injected as part of the
+command line each call of the option on the command line will result in a
+separate element of the outer vector. This can be manually controlled via
+`inject_separator(true|false)` but in nearly all cases this should be left to
+the defaults. To insert of a separator from the command line add a `%%` where
+the separation should occur.
  
 ```bash
 cmd --vec_of_vec 1 2 3 4 %% 1 2
 ```
  
-would then result in a container of size 2 with the first element containing 4 values and the second 2.
+would then result in a container of size 2 with the first element containing 4
+values and the second 2.
  
 This separator is also the only way to get values into something like
  
@@ -130,7 +177,8 @@ app.add_option(&quot;--vec&quot;, two_vecs, &quot;pair of vectors&quot;);
  
 without calling the argument twice.
  
-Further levels of nesting containers should compile but intermediate layers will only have a single element in the container, so is probably not that useful.
+Further levels of nesting containers should compile but intermediate layers will
+only have a single element in the container, so is probably not that useful.
  
 ### Nested types
  
@@ -141,18 +189,21 @@ std::map&lt;int, std::pair&lt;int,std::string&gt;&gt; map;
 app.add_option("--dict", map, "map of pairs");
 ```
  
-will require 3 arguments for each invocation, and multiple sets of 3 arguments can be entered for a single invocation on the command line.
+will require 3 arguments for each invocation, and multiple sets of 3 arguments
+can be entered for a single invocation on the command line.
  
 ```cpp
 std::map<int, std::pair<int,std::vector<std::string>>> map;
 app.add_option("--dict", map, "map of pairs");
 ```
  
-will result in a requirement for 2 integers on each invocation and absorb an unlimited number of strings including 0.
+will result in a requirement for 2 integers on each invocation and absorb an
+unlimited number of strings including 0.
  
 ## Option modifiers
  
-When you call `add_option`, you get a pointer to the added option. You can use that to add option modifiers. A full listing of the option modifiers:
+When you call `add_option`, you get a pointer to the added option. You can use
+that to add option modifiers. A full listing of the option modifiers:
  
 | Modifier                                                | Description                                                                                                                                                                                                                                                                                                                                                                                                                                               |
 | ------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
@@ -190,11 +241,19 @@ When you call `add_option`, you get a pointer to the added option. You can use t
 | `->trigger_on_parse()`                                  | Have the option callback be triggered when the value is parsed vs. at the end of all parsing, the option callback can potentially be executed multiple times. Generally only useful if you have a user defined callback or validation check. Or potentially if a vector input is given multiple times as it will clear the results when a repeat option is given via command line. It will trigger the callbacks once per option call on the command line |
 | `->option_text(string)`                                 | Sets the text between the option name and description.                                                                                                                                                                                                                                                                                                                                                                                                    |
  
-The `->check(...)` and `->transform(...)` modifiers can also take a callback function of the form `bool function(std::string)` that runs on every value that the option receives, and returns a value that tells CLI11 whether the check passed or failed.
+The `->check(...)` and `->transform(...)` modifiers can also take a callback
+function of the form `bool function(std::string)` that runs on every value that
+the option receives, and returns a value that tells CLI11 whether the check
+passed or failed.
  
 ## Using the `CLI::Option` pointer
  
-Each of the option creation mechanisms returns a pointer to the internally stored option. If you save that pointer, you can continue to access the option, and change setting on it later. The Option object can also be converted to a bool to see if it was passed, or `->count()` can be used to see how many times the option was passed. Since flags are also options, the same methods work on them.
+Each of the option creation mechanisms returns a pointer to the internally
+stored option. If you save that pointer, you can continue to access the option,
+and change setting on it later. The Option object can also be converted to a
+bool to see if it was passed, or `->count()` can be used to see how many times
+the option was passed. Since flags are also options, the same methods work on
+them.
  
 ```cpp
 CLI::Option* opt = app.add_flag("--opt");
@@ -207,17 +266,33 @@ if(* opt)
  
 ## Inheritance of defaults
  
-One of CLI11's systems to allow customizability without high levels of verbosity is the inheritance system. You can set default values on the parent `App`, and all options and subcommands created from it remember the default values at the point of creation. The default value for Options, specifically, are accessible through the `option_defaults()` method. There are a number of settings that can be set and inherited:
+One of CLI11's systems to allow customizability without high levels of verbosity
+is the inheritance system. You can set default values on the parent `App`, and
+all options and subcommands created from it remember the default values at the
+point of creation. The default value for Options, specifically, are accessible
+through the `option_defaults()` method. There are a number of settings that can
+be set and inherited:
  
 - `group`: The group name starts as "Options"
-- `required`: If the option must be given. Defaults to `false`. Is ignored for flags.
-- `multi_option_policy`: What to do if several copies of an option are passed and one value is expected. Defaults to `CLI::MultiOptionPolicy::Throw`. This is also used for bool flags, but they always are created with the value `CLI::MultiOptionPolicy::TakeLast` or `CLI::MultiOptionPolicy::Sum` regardless of the default, so that multiple bool flags does not cause an error. But you can override that setting by calling the `multi_option_policy` directly.
+- `required`: If the option must be given. Defaults to `false`. Is ignored for
+  flags.
+- `multi_option_policy`: What to do if several copies of an option are passed
+  and one value is expected. Defaults to `CLI::MultiOptionPolicy::Throw`. This
+  is also used for bool flags, but they always are created with the value
+  `CLI::MultiOptionPolicy::TakeLast` or `CLI::MultiOptionPolicy::Sum` regardless
+  of the default, so that multiple bool flags does not cause an error. But you
+  can override that setting by calling the `multi_option_policy` directly.
 - `ignore_case`: Allow any mixture of cases for the option or flag name
-- `ignore_underscore`: Allow any number of underscores in the option or flag name
-- `configurable`: Specify whether an option can be configured through a config file
-- `disable_flag_override`: do not allow flag values to be overridden on the command line
-- `always_capture_default`: specify that the default values should be automatically captured.
-- `delimiter`: A delimiter to use for capturing multiple values in a single command line string (e.g. --flag="flag,-flag2,flag3")
+- `ignore_underscore`: Allow any number of underscores in the option or flag
+  name
+- `configurable`: Specify whether an option can be configured through a config
+  file
+- `disable_flag_override`: do not allow flag values to be overridden on the
+  command line
+- `always_capture_default`: specify that the default values should be
+  automatically captured.
+- `delimiter`: A delimiter to use for capturing multiple values in a single
+  command line string (e.g. --flag="flag,-flag2,flag3")
  
 An example of usage:
  
@@ -228,11 +303,13 @@ app.add_flag(&quot;--CaSeLeSs&quot;);
 app.get_group() // is "Required"
 ```
  
-Groups are mostly for visual organization, but an empty string for a group name will hide the option.
+Groups are mostly for visual organization, but an empty string for a group name
+will hide the option.
  
 ### Windows style options
  
-You can also set the app setting `app->allow_windows_style_options()` to allow windows style options to also be recognized on the command line:
+You can also set the app setting `app->allow_windows_style_options()` to allow
+windows style options to also be recognized on the command line:
  
 - `/a` (flag)
 - `/f filename` (option)
@@ -241,11 +318,23 @@ You can also set the app setting `app-&gt;allow_windows_style_options()` to allow w
 - `/file:filename` (colon)
 - `/long_flag:false` (long flag with : to override the default value)
  
-Windows style options do not allow combining short options or values not separated from the short option like with `-` options. You still specify option names in the same manner as on Linux with single and double dashes when you use the `add_*` functions, and the Linux style on the command line will still work. If a long and a short option share the same name, the option will match on the first one defined.
+Windows style options do not allow combining short options or values not
+separated from the short option like with `-` options. You still specify option
+names in the same manner as on Linux with single and double dashes when you use
+the `add_*` functions, and the Linux style on the command line will still work.
+If a long and a short option share the same name, the option will match on the
+first one defined.
  
 ## Parse configuration
  
-How an option and its arguments are parsed depends on a set of controls that are part of the option structure. In most circumstances these controls are set automatically based on the type or function used to create the option and the type the arguments are parsed into. The variables define the size of the underlying type (essentially how many strings make up the type), the expected size (how many groups are expected) and a flag indicating if multiple groups are allowed with a single option. And these interact with the `multi_option_policy` when it comes time to parse.
+How an option and its arguments are parsed depends on a set of controls that are
+part of the option structure. In most circumstances these controls are set
+automatically based on the type or function used to create the option and the
+type the arguments are parsed into. The variables define the size of the
+underlying type (essentially how many strings make up the type), the expected
+size (how many groups are expected) and a flag indicating if multiple groups are
+allowed with a single option. And these interact with the `multi_option_policy`
+when it comes time to parse.
  
 ### Examples
  
@@ -256,7 +345,12 @@ std::string val;
 app.add_option("--opt",val,"description");
 ```
  
-creates an option that assigns a value to a `std::string` When this option is constructed it sets a type_size min and max of 1. Meaning that the assignment uses a single string. The Expected size is also set to 1 by default, and `allow_extra_args` is set to false. meaning that each time this option is called 1 argument is expected. This would also be the case if val were a `double`, `int` or any other single argument types.
+creates an option that assigns a value to a `std::string` When this option is
+constructed it sets a type_size min and max of 1. Meaning that the assignment
+uses a single string. The Expected size is also set to 1 by default, and
+`allow_extra_args` is set to false. meaning that each time this option is called
+1 argument is expected. This would also be the case if val were a `double`,
+`int` or any other single argument types.
  
 now for example
  
@@ -265,35 +359,49 @@ std::pair&lt;int, std::string&gt; val;
 app.add_option("--opt",val,"description");
 ```
  
-In this case the typesize is automatically detected to be 2 instead of 1, so the parsing would expect 2 arguments associated with the option.
+In this case the typesize is automatically detected to be 2 instead of 1, so the
+parsing would expect 2 arguments associated with the option.
  
 ```cpp
 std::vector<int> val;
 app.add_option("--opt",val,"description");
 ```
  
-detects a type size of 1, since the underlying element type is a single string, so the minimum number of strings is 1. But since it is a vector the expected number can be very big. The default for a vector is (1<<30), and the allow_extra_args is set to true. This means that at least 1 argument is expected to follow the option, but arbitrary numbers of arguments may follow. These are checked if they have the form of an option but if not they are added to the argument.
+detects a type size of 1, since the underlying element type is a single string,
+so the minimum number of strings is 1. But since it is a vector the expected
+number can be very big. The default for a vector is (1<<30), and the
+allow_extra_args is set to true. This means that at least 1 argument is expected
+to follow the option, but arbitrary numbers of arguments may follow. These are
+checked if they have the form of an option but if not they are added to the
+argument.
  
 ```cpp
 std::vector<std::tuple<int, double, std::string>> val;
 app.add_option("--opt",val,"description");
 ```
  
-gets into the complicated cases where the type size is now 3. and the expected max is set to a large number and `allow_extra_args` is set to true. In this case at least 3 arguments are required to follow the option, and subsequent groups must come in groups of three, otherwise an error will result.
+gets into the complicated cases where the type size is now 3. and the expected
+max is set to a large number and `allow_extra_args` is set to true. In this case
+at least 3 arguments are required to follow the option, and subsequent groups
+must come in groups of three, otherwise an error will result.
  
 ```cpp
 bool val{false};
 app.add_flag("--opt",val,"description");
 ```
  
-Using the add_flag methods for creating options creates an option with an expected size of 0, implying no arguments can be passed.
+Using the add_flag methods for creating options creates an option with an
+expected size of 0, implying no arguments can be passed.
  
 ```cpp
 std::complex<double> val;
 app.add_option("--opt",val,"description");
 ```
  
-triggers the complex number type which has a min of 1 and max of 2, so 1 or 2 strings can be passed. Complex number conversion supports arguments of the form "1+2j" or "1","2", or "1" "2i". The imaginary number symbols `i` and `j` are interchangeable in this context.
+triggers the complex number type which has a min of 1 and max of 2, so 1 or 2
+strings can be passed. Complex number conversion supports arguments of the form
+"1+2j" or "1","2", or "1" "2i". The imaginary number symbols `i` and `j` are
+interchangeable in this context.
  
 ```cpp
 std::vector<std::vector<int>> val;
@@ -304,7 +412,9 @@ has a type size of 1 to (1&lt;&lt;30).
  
 ### Customization
  
-The `type_size(N)`, `type_size(Nmin, Nmax)`, `expected(N)`, `expected(Nmin,Nmax)`, and `allow_extra_args()` can be used to customize an option. For example
+The `type_size(N)`, `type_size(Nmin, Nmax)`, `expected(N)`,
+`expected(Nmin,Nmax)`, and `allow_extra_args()` can be used to customize an
+option. For example
  
 ```cpp
 std::string val;
@@ -312,16 +422,38 @@ auto opt=app.add_flag(&quot;--opt{vvv}&quot;,val,&quot;description&quot;);
 opt->expected(0,1);
 ```
  
-will create a hybrid option, that can exist on its own in which case the value "vvv" is used or if a value is given that value will be used.
+will create a hybrid option, that can exist on its own in which case the value
+"vvv" is used or if a value is given that value will be used.
  
-There are some additional options that can be specified to modify an option for specific cases:
+There are some additional options that can be specified to modify an option for
+specific cases:
  
-- `->run_callback_for_default()` will specify that the callback should be executed when a default_val is set. This is set automatically when appropriate though it can be turned on or off and any user specified callback for an option will be executed when the default value for an option is set.
+- `->run_callback_for_default()` will specify that the callback should be
+  executed when a default_val is set. This is set automatically when appropriate
+  though it can be turned on or off and any user specified callback for an
+  option will be executed when the default value for an option is set.
  
-- `->force_callback()` will for the callback/value assignment to run at the conclusion of parsing regardless of whether the option was supplied or not. This can be used to force the default or execute some code.
+- `->force_callback()` will for the callback/value assignment to run at the
+  conclusion of parsing regardless of whether the option was supplied or not.
+  This can be used to force the default or execute some code.
  
-- `->trigger_on_parse()` will trigger the callback or value assignment each time the argument is passed. The value is reset if the option is supplied multiple times.
+- `->trigger_on_parse()` will trigger the callback or value assignment each time
+  the argument is passed. The value is reset if the option is supplied multiple
+  times.
  
 ## Unusual circumstances
  
-There are a few cases where some things break down in the type system managing options and definitions. Using the `add_option` method defines a lambda function to extract a default value if required. In most cases this is either straightforward or a failure is detected automatically and handled. But in a few cases a streaming template is available that several layers down may not actually be defined. This results in CLI11 not being able to detect this circumstance automatically and will result in compile error. One specific known case is `boost::optional` if the boost optional_io header is included. This header defines a template for all boost optional values even if they do not actually have a streaming operator. For example `boost::optional<std::vector>` does not have a streaming operator but one is detected since it is part of a template. For these cases a secondary method `app->add_option_no_stream(...)` is provided that bypasses this operation completely and should compile in these cases.
+There are a few cases where some things break down in the type system managing
+options and definitions. Using the `add_option` method defines a lambda function
+to extract a default value if required. In most cases this is either
+straightforward or a failure is detected automatically and handled. But in a few
+cases a streaming template is available that several layers down may not
+actually be defined. This results in CLI11 not being able to detect this
+circumstance automatically and will result in compile error. One specific known
+case is `boost::optional` if the boost optional_io header is included. This
+header defines a template for all boost optional values even if they do not
+actually have a streaming operator. For example `boost::optional<std::vector>`
+does not have a streaming operator but one is detected since it is part of a
+template. For these cases a secondary method `app->add_option_no_stream(...)` is
+provided that bypasses this operation completely and should compile in these
+cases.
 # Subcommands and the App
  
-Subcommands are keyword that invoke a new set of options and features. For example, the `git`
-command has a long series of subcommands, like `add` and `commit`. Each can have its own options
-and implementations. This chapter will focus on implementations that are contained in the same
-C++ application, though the system git uses to extend the main command by calling other commands
-in separate executables is supported too; that's called "Prefix commands" and is included at the
-end of this chapter.
+Subcommands are keyword that invoke a new set of options and features. For
+example, the `git` command has a long series of subcommands, like `add` and
+`commit`. Each can have its own options and implementations. This chapter will
+focus on implementations that are contained in the same C++ application, though
+the system git uses to extend the main command by calling other commands in
+separate executables is supported too; that's called "Prefix commands" and is
+included at the end of this chapter.
  
 ## The parent App
  
-We'll start by discussing the parent `App`. You've already used it quite a bit, to create
-options and set option defaults. There are several other things you can do with an `App`, however.
+We'll start by discussing the parent `App`. You've already used it quite a bit,
+to create options and set option defaults. There are several other things you
+can do with an `App`, however.
  
-You are given a lot of control the help output. You can set a footer with `app.footer("My Footer")`.
-You can replace the default help print when a `ParseError` is thrown with `app.set_failure_message(CLI::FailureMessage::help)`.
-The default is `CLI:::FailureMessage::simple`, and you can easily define a new one. Just make a (lambda) function that takes an App pointer
-and a reference to an error code (even if you don't use them), and returns a string.
+You are given a lot of control the help output. You can set a footer with
+`app.footer("My Footer")`. You can replace the default help print when a
+`ParseError` is thrown with
+`app.set_failure_message(CLI::FailureMessage::help)`. The default is
+`CLI:::FailureMessage::simple`, and you can easily define a new one. Just make a
+(lambda) function that takes an App pointer and a reference to an error code
+(even if you don't use them), and returns a string.
  
 ## Adding a subcommand
  
@@ -25,12 +30,14 @@ Subcommands can be added just like an option:
 CLI::App* sub = app.add_subcommand("sub", "This is a subcommand");
 ```
  
-The subcommand should have a name as the first argument, and a little description for the
-second argument. A pointer to the internally stored subcommand is provided; you usually will
-be capturing that pointer and using it later (though you can use callbacks if you prefer). As
-always, feel free to use `auto sub = ...` instead of naming the type.
+The subcommand should have a name as the first argument, and a little
+description for the second argument. A pointer to the internally stored
+subcommand is provided; you usually will be capturing that pointer and using it
+later (though you can use callbacks if you prefer). As always, feel free to use
+`auto sub = ...` instead of naming the type.
  
-You can check to see if the subcommand was received on the command line several ways:
+You can check to see if the subcommand was received on the command line several
+ways:
  
 ```cpp
 if(*sub) ...
@@ -39,39 +46,53 @@ if(app.got_subcommand(sub)) ...
 if(app.got_subcommand("sub")) ...
 ```
  
-You can also get a list of subcommands with `get_subcommands()`, and they will be in parsing order.
+You can also get a list of subcommands with `get_subcommands()`, and they will
+be in parsing order.
  
 There are a lot of options that you can set on a subcommand; in fact,
-subcommands have exactly the same options as your main app, since they are actually
-the same class of object (as you may have guessed from the type above). This has the
-pleasant side affect of making subcommands infinitely nestable.
+subcommands have exactly the same options as your main app, since they are
+actually the same class of object (as you may have guessed from the type above).
+This has the pleasant side affect of making subcommands infinitely nestable.
  
 ## Required subcommands
  
-Each App has controls to set the number of subcommands you expect. This is controlled by:
+Each App has controls to set the number of subcommands you expect. This is
+controlled by:
  
 ```cpp
 app.require_subcommand(/* min */ 0, /* max */ 1);
 ```
  
-If you set the max to 0, CLI11 will allow an unlimited number of subcommands. After the (non-unlimited) maximum
-is reached, CLI11 will stop trying to match subcommands. So the if you pass "`one two`" to a command, and both `one`
-and `two` are subcommands, it will depend on the maximum number as to whether the "`two`" is a subcommand or an argument to the
-"`one`" subcommand.
+If you set the max to 0, CLI11 will allow an unlimited number of subcommands.
+After the (non-unlimited) maximum is reached, CLI11 will stop trying to match
+subcommands. So the if you pass "`one two`" to a command, and both `one` and
+`two` are subcommands, it will depend on the maximum number as to whether the
+"`two`" is a subcommand or an argument to the "`one`" subcommand.
  
-As a shortcut, you can also call the `require_subcommand` method with one argument; that will be the fixed number of subcommands if positive, it
-will be the maximum number if negative. Calling it without an argument will set the required subcommands to 1 or more.
+As a shortcut, you can also call the `require_subcommand` method with one
+argument; that will be the fixed number of subcommands if positive, it will be
+the maximum number if negative. Calling it without an argument will set the
+required subcommands to 1 or more.
  
-The maximum number of subcommands is inherited by subcommands. This allows you to set the maximum to 1 once at the beginning on the parent app if you only want single subcommands throughout your app. You should keep this in mind, if you are dealing with lots of nested subcommands.
+The maximum number of subcommands is inherited by subcommands. This allows you
+to set the maximum to 1 once at the beginning on the parent app if you only want
+single subcommands throughout your app. You should keep this in mind, if you are
+dealing with lots of nested subcommands.
  
 ## Using callbacks
  
-You've already seen how to check to see what subcommands were given. It's often much easier, however, to just define the code you want to run when you are making your parser, and not run a bunch of code after `CLI11_PARSE` to analyse the state (Procedural! Yuck!). You can do that with lambda functions. A `std::function<void()>` callback `.callback()` is provided, and CLI11 ensures that all options are prepared and usable by reference capture before entering the callback. An
-example is shown below in the `geet` program.
+You've already seen how to check to see what subcommands were given. It's often
+much easier, however, to just define the code you want to run when you are
+making your parser, and not run a bunch of code after `CLI11_PARSE` to analyse
+the state (Procedural! Yuck!). You can do that with lambda functions. A
+`std::function<void()>` callback `.callback()` is provided, and CLI11 ensures
+that all options are prepared and usable by reference capture before entering
+the callback. An example is shown below in the `geet` program.
  
 ## Inheritance of defaults
  
-The following values are inherited when you add a new subcommand. This happens at the point the subcommand is created:
+The following values are inherited when you add a new subcommand. This happens
+at the point the subcommand is created:
  
 - The name and description for the help flag
 - The footer
@@ -94,28 +115,39 @@ There are several special modes for Apps and Subcommands.
  
 ### Allow extras
  
-Normally CLI11 throws an error if you don't match all items given on the command line. However, you can enable `allow_extras()`
-to instead store the extra values in `.remaining()`. You can get all remaining options including those in contained subcommands recursively in the original order with `.remaining(true)`.
-`.remaining_size()` is also provided; this counts the size but ignores the `--` special separator if present.
+Normally CLI11 throws an error if you don't match all items given on the command
+line. However, you can enable `allow_extras()` to instead store the extra values
+in `.remaining()`. You can get all remaining options including those in
+contained subcommands recursively in the original order with `.remaining(true)`.
+`.remaining_size()` is also provided; this counts the size but ignores the `--`
+special separator if present.
  
 ### Fallthrough
  
-Fallthrough allows an option that does not match in a subcommand to "fall through" to the parent command; if that parent
-allows that option, it matches there instead. This was added to allow CLI11 to represent models:
+Fallthrough allows an option that does not match in a subcommand to "fall
+through" to the parent command; if that parent allows that option, it matches
+there instead. This was added to allow CLI11 to represent models:
  
 ```term
 gitbook:code $ ./my_program my_model_1 --model_flag --shared_flag
 ```
  
-Here, `--shared_flag` was set on the main app, and on the command line it "falls through" `my_model_1` to match on the main app.
+Here, `--shared_flag` was set on the main app, and on the command line it "falls
+through" `my_model_1` to match on the main app.
  
 ### Prefix command
  
-This is a special mode that allows "prefix" commands, where the parsing completely stops when it gets to an unknown option. Further unknown options are ignored, even if they could match. Git is the traditional example for prefix commands; if you run git with an unknown subcommand, like "`git thing`", it then calls another command called "`git-thing`" with the remaining options intact.
+This is a special mode that allows "prefix" commands, where the parsing
+completely stops when it gets to an unknown option. Further unknown options are
+ignored, even if they could match. Git is the traditional example for prefix
+commands; if you run git with an unknown subcommand, like "`git thing`", it then
+calls another command called "`git-thing`" with the remaining options intact.
  
 ### Silent subcommands
  
-Subcommands can be modified by using the `silent` option. This will prevent the subcommand from showing up in the get_subcommands list. This can be used to make subcommands into modifiers. For example, a help subcommand might look like
+Subcommands can be modified by using the `silent` option. This will prevent the
+subcommand from showing up in the get_subcommands list. This can be used to make
+subcommands into modifiers. For example, a help subcommand might look like
  
 ```c++
     auto sub1 = app.add_subcommand("help")->silent();
@@ -131,11 +163,19 @@ This would allow calling help such as:
  
 ### Positional Validation
  
-Some arguments supplied on the command line may be legitamately applied to more than 1 positional argument. In this context enabling `positional_validation` on the application or subcommand will check any validators before applying the command line argument to the positional option. It is not an error to fail validation in this context, positional arguments not matching any validators will go into the `extra_args` field which may generate an error depending on settings.
+Some arguments supplied on the command line may be legitamately applied to more
+than 1 positional argument. In this context enabling `positional_validation` on
+the application or subcommand will check any validators before applying the
+command line argument to the positional option. It is not an error to fail
+validation in this context, positional arguments not matching any validators
+will go into the `extra_args` field which may generate an error depending on
+settings.
  
 ### Optional Argument Validation
  
-Similar to positional validation, there are occasional contexts in which case it might be ambiguous whether an argument should be applied to an option or a positional option.
+Similar to positional validation, there are occasional contexts in which case it
+might be ambiguous whether an argument should be applied to an option or a
+positional option.
  
 ```c++
     std::vector<std::string> vec;
@@ -145,4 +185,10 @@ Similar to positional validation, there are occasional contexts in which case it
     app.validate_optional_arguments();
 ```
  
-In this case a sequence of integers is expected for the argument and remaining strings go to the positional string vector. Without the `validate_optional_arguments()` active it would be impossible get any later arguments into the positional if the `--args` option is used. The validator in this context is used to make sure the optional arguments match with what the argument is expecting and if not the `-args` option is closed, and remaining arguments fall into the positional.
+In this case a sequence of integers is expected for the argument and remaining
+strings go to the positional string vector. Without the
+`validate_optional_arguments()` active it would be impossible get any later
+arguments into the positional if the `--args` option is used. The validator in
+this context is used to make sure the optional arguments match with what the
+argument is expecting and if not the `-args` option is closed, and remaining
+arguments fall into the positional.
 # Using CLI11 in a Toolkit
  
-CLI11 was designed to be integrate into a toolkit, providing a native experience for users. This was used in GooFit to provide `GooFit::Application`, an class designed to make ROOT users feel at home.
+CLI11 was designed to be integrate into a toolkit, providing a native experience
+for users. This was used in GooFit to provide `GooFit::Application`, an class
+designed to make ROOT users feel at home.
  
 ## Custom namespace
  
-If you want to provide CLI11 in a custom namespace, you'll want to at least put `using CLI::App` in your namespace. You can also include Option, some errors, and validators. You can also put `using namespace CLI` inside your namespace to import everything.
+If you want to provide CLI11 in a custom namespace, you'll want to at least put
+`using CLI::App` in your namespace. You can also include Option, some errors,
+and validators. You can also put `using namespace CLI` inside your namespace to
+import everything.
  
-You may also want to make your own copy of the `CLI11_PARSE` macro. Something like:
+You may also want to make your own copy of the `CLI11_PARSE` macro. Something
+like:
  
 ```cpp
  #define MYPACKAGE_PARSE(app, argv, argc)    \
@@ -19,10 +25,16 @@ You may also want to make your own copy of the `CLI11_PARSE` macro. Something li
  
 ## Subclassing App
  
-If you subclass `App`, you'll just need to do a few things. You'll need a constructor; calling the base `App` constructor is a good idea, but not necessary (it just sets a description and adds a help flag.
+If you subclass `App`, you'll just need to do a few things. You'll need a
+constructor; calling the base `App` constructor is a good idea, but not
+necessary (it just sets a description and adds a help flag.
  
-You can call anything you would like to configure in the constructor, like `option_defaults()->take_last()` or `fallthrough()`, and it will be set on all user instances. You can add flags and options, as well.
+You can call anything you would like to configure in the constructor, like
+`option_defaults()->take_last()` or `fallthrough()`, and it will be set on all
+user instances. You can add flags and options, as well.
  
 ## Virtual functions provided
  
-You are given a few virtual functions that you can change (only on the main App). `pre_callback` runs right before the callbacks run, letting you print out custom messages at the top of your app.
+You are given a few virtual functions that you can change (only on the main
+App). `pre_callback` runs right before the callbacks run, letting you print out
+custom messages at the top of your app.
@@ -3,22 +3,26 @@
 There are two forms of validators:
  
 - `transform` validators: mutating
-- `check` validators: non-mutating (recommended unless the parsed string must be mutated)
+- `check` validators: non-mutating (recommended unless the parsed string must be
+  mutated)
  
-A transform validator comes in one form, a function with the signature `std::string(std::string)`.
-The function will take a string and return the modified version of the string. If there is an error,
-the function should throw a `CLI::ValidationError` with the appropriate reason as a message.
+A transform validator comes in one form, a function with the signature
+`std::string(std::string)`. The function will take a string and return the
+modified version of the string. If there is an error, the function should throw
+a `CLI::ValidationError` with the appropriate reason as a message.
  
-However, `check` validators come in two forms; either a simple function with the const version of the
-above signature, `std::string(const std::string &)`, or a subclass of `struct CLI::Validator`. This
-structure has two members that a user should set; one (`func_`) is the function to add to the Option
-(exactly matching the above function signature, since it will become that function), and the other is
-`name_`, and is the type name to set on the Option (unless empty, in which case the typename will be
-left unchanged).
+However, `check` validators come in two forms; either a simple function with the
+const version of the above signature, `std::string(const std::string &)`, or a
+subclass of `struct CLI::Validator`. This structure has two members that a user
+should set; one (`func_`) is the function to add to the Option (exactly matching
+the above function signature, since it will become that function), and the other
+is `name_`, and is the type name to set on the Option (unless empty, in which
+case the typename will be left unchanged).
  
-Validators can be combined with `&` and `|`, and they have an `operator()` so that you can call them
-as if they were a function. In CLI11, const static versions of the validators are provided so that
-the user does not have to call a constructor also.
+Validators can be combined with `&` and `|`, and they have an `operator()` so
+that you can call them as if they were a function. In CLI11, const static
+versions of the validators are provided so that the user does not have to call a
+constructor also.
  
 An example of a custom validator:
  
@@ -37,7 +41,8 @@ struct LowerCaseValidator : public Validator {
 const static LowerCaseValidator Lowercase;
 ```
  
-If you were not interested in the extra features of Validator, you could simply pass the lambda function above to the `->check()` method of `Option`.
+If you were not interested in the extra features of Validator, you could simply
+pass the lambda function above to the `->check()` method of `Option`.
  
 The built-in validators for CLI11 are:
  
 # Introduction {#mainpage}
  
-This is the Doxygen API documentation for CLI11 parser. There is a friendly introduction to CLI11 on the [GitHub page](https://github.com/CLIUtils/CLI11), and [a tutorial series](https://cliutils.github.io/CLI11/book/).
+This is the Doxygen API documentation for CLI11 parser. There is a friendly
+introduction to CLI11 on the [GitHub page](https://github.com/CLIUtils/CLI11),
+and [a tutorial series](https://cliutils.github.io/CLI11/book/).
  
 The main classes are: