Invalid unicode support for default_value

[anonymous]

The following example could not be compiled: =================================================================

#include <string> #include <boost/program_options.hpp>

namespace po = boost::program_options;

int main() {

std::wstring test; po::options_description desc("Allowed options"); desc.add_options()

("test", po::wvalue<std::wstring>(&test)->default_value(L"value"), "description");

}

=================================================================

It is due to wvalue::default_value tries to do lexical_cast<std::string>(std::wstring). Also I cannot change default_value to default_value("value") as soon as it accepts only something convertible to std::wstring. In other words it is impossible to specify default_value for wstring option.

[Sascha Ochsenknecht <s.ochsenknecht@…>]

This problem appears for every value type which makes problem with lexical_cast<std::string>().

Here is a workaround: There as an overloaded version of default_value() which can be used to define the string representation of the default value:

("test", po::value<std::wstring>()->default_value(L"value", "value"), "description.") 

This string (second parameter of default_value()) is then used for the help output. I would recommend to use this approach.

Please comment.

[Vladimir Prus]

I agree that explicitly specifying the textual rendition of default value is the best approach for now.