Fix handling of implicit values

Fixes #84. Implicit values are not handled very well. For example: --foo false true --foo --bar In the first, `false` is an argument to `--foo`, and then `true` is a positional argument. In the second, because of the hyphen in `--bar`, `--foo` is parsed with its implicit value. This seems inconsistent and unintuitive. Better is that implicit values *never* consume the next parameter to be completely consistent. This means that values with an implicit parameter *must* be specified using the `--option=value` form.

Fix handling of implicit values
Fixes #84. Implicit values are not handled very well. For example: --foo false true --foo --bar In the first, `false` is an argument to `--foo`, and then `true` is a positional argument. In the second, because of the hyphen in `--bar`, `--foo` is parsed with its implicit value. This seems inconsistent and unintuitive. Better is that implicit values *never* consume the next parameter to be completely consistent. This means that values with an implicit parameter *must* be specified using the `--option=value` form.
Jarryd Beck
1 parent 0a49b820
Showing 3 changed files with 14 additions and 4 deletions
CHANGELOG.md
include/cxxopts.hpp
test/options.cpp
@@ -3,6 +3,16 @@
 This is the changelog for `cxxopts`, a C++11 library for parsing command line
 options. The project adheres to semantic versioning.
+## 2.1
+
+### Changed
+
+* Options with implicit arguments now require the `--option=value` form if
+  they are to be specified with an option. This is to remove the ambiguity
+  when a positional argument could follow an option with an implicit value.
+  For example, `--foo value`, where `foo` has an implicit value, will be
+  parsed as `--foo=implicit` and a positional argument `value`.
+
 ## 2.0
 ### Changed
@@ -1522,7 +1522,7 @@ ParseResult::checked_parse_arg
   }
   else
   {
-    if (argv[current + 1][0] == '-' && value->value().has_implicit())
+    if (value->value().has_implicit())
     {
       parse_option(value, name, value->value().get_implicit_value());
     }
@@ -1696,7 +1696,7 @@ ParseResult::parse(int&amp; argc, char**&amp; argv)
         auto opt = iter->second;
         //equals provided for long option?
-        if (result[3].length() != 0)
+        if (result[2].length() != 0)
         {
           //parse the option given
@@ -218,7 +218,7 @@ TEST_CASE(&quot;Empty with implicit value&quot;, &quot;[implicit]&quot;)
     ("implicit", "Has implicit", cxxopts::value<std::string>()
       ->implicit_value("foo"));
-  Argv av({"implicit", "--implicit", ""});
+  Argv av({"implicit", "--implicit="});
   char** argv = av.argv();
   auto argc = av.argc();
@@ -428,7 +428,7 @@ TEST_CASE(&quot;Booleans&quot;, &quot;[boolean]&quot;) {
   options.parse_positional("others");
-  Argv av({"booleans", "--bool=false", "--debug", "true", "--timing", "extra"});
+  Argv av({"booleans", "--bool=false", "--debug=true", "--timing", "extra"});
   char** argv = av.argv();
   auto argc = av.argc();