Method put_value

src/Settings.cpp:66–73

        return value;
    }
    inline boost::optional<internal_type> put_value(const external_type &v) const {
        std::basic_ostringstream<Ch, Traits, Alloc> stream;
        customizeA::insert(stream, v.first);
        stream << " ";
        customizeB::insert(stream, v.second);
        if (stream) return stream.str();
        else return { };
    }
};
template <typename Source, typename A, typename B>
struct get_pair_translator {