Re: [Boost-users] program_options, parse_config_file problems

Subject: Re: [Boost-users] program_options, parse_config_file problems
From: Jeffrey Lee Hellrung, Jr. (jeffrey.hellrung_at_[hidden])
Date: 2012-04-25 22:44:28

On Wed, Apr 25, 2012 at 5:48 PM, Andrew E Slaughter <
andrew.e.slaughter_at_[hidden]> wrote:

> Hello,
>
> I am attempting to parse configuration options from a file using
> Boost::program_options. I am following the example provided on the website (
> http://www.boost.org/doc/**libs/1_49_0/doc/html/program_**
> options/overview.html#**id2501135<http://www.boost.org/doc/libs/1_49_0/doc/html/program_options/overview.html#id2501135>
> ):
>
> variables_map vm;
> store(parse_command_line(argc, argv, desc), vm);
> store(parse_config_file("**example.cfg", desc), vm);
> notify(vm);
>
> I have included the following related to program_options:
> #include <boost/program_options.hpp> // Boost Program Options
> #include <boost/program_options/**positional_options.hpp>
> #include <boost/program_options/**parsers.hpp>
>
> I have the exact code as above in my program but receive the following
> error. The program works fine if I comment out the line with the
> parse_config_file line. Can someone please help me get this working.
>
> Thanks,
> Andrew
>
> --- COMPILER ERROR --------------------------
> /home/slaughter/Documents/**programs/source/common/user_**options/user_options.cpp:
> In member function ‘void SlaughterCommon::User_options:**:apply_options(int,
> char**)’:
> /home/slaughter/Documents/**programs/source/common/user_**
> options/user_options.cpp:27:**76: error: no matching function for call to
> ‘parse_config_file(const char [22], boost::program_options::**options_description&,
> bool)’
> /home/slaughter/Documents/**programs/source/common/user_**
> options/user_options.cpp:27:**76: note: candidates are:
> /usr/include/boost/program_**options/parsers.hpp:163:5: note:
> template<class charT> boost::program_options::basic_**parsed_options<charT>
> boost::program_options::parse_**config_file(std::basic_**istream<charT>&,
> const boost::program_options::**options_description&, bool)
> /usr/include/boost/program_**options/parsers.hpp:176:5: note:
> template<class charT> boost::program_options::basic_**parsed_options<charT>
> boost::program_options::parse_**config_file(const char*, const
> boost::program_options::**options_description&, bool)
>
[...snip...]

So this overload looks like the one you want, but it has a non-deduced
template parameter charT (which should probably be deduced to be char? I'm
not sure). I got the short program below to compile by explicitly
specifying the charT template parameter as char.

#include <boost/program_options.hpp>

int main(int argc, char* argv[])
{
    using namespace boost::program_options;
    options_description desc;
    variables_map vm;
    store(parse_command_line(argc, argv, desc), vm);
    store(parse_config_file< char >("example.cfg", desc), vm);
    notify(vm);
    return 0;
}

Please file a trac ticket alerting the Boost.ProgramOptions maintainer of
the compiler failure of the example snippet in the docs.

HTH,

- Jeff