Function to_string

extern/boost/boost/exception/to_string.hpp:59–66

    template <class T>
    inline
    typename enable_if<is_output_streamable<T>,std::string>::type
    to_string( T const & x )
        {
        std::ostringstream out;
        out << x;
        return out.str();
        }

    template <class T>
    struct