convert::to_string<wstring>, convert::to_integral<int, rounding::down>, convert::transcode_string<wstring, native_mbcs>, ...
How about convert::to<wstring> convert::to<int, rounding::down> convert::to<wstring, native_mbcs> I am serious. I actually like it. I understand you do not like my to/from but you are almost there. By eliminating the repetition (as for _string<wstring) we get a laconic and expressive (IMHO of course) interface. No need for various to_string, to_integral, transcode_string, etc. We get rid of the string namespace as well (it should be a plus isn't it?). So, it'd be int i = boost::convert::to<int>(str); // explicit 'int' type int i = boost::convert::to(str, -1); // deduced 'int' string s = boost::convert::to<string>(-1); // explicit std::string type string s = boost::convert::to(-1, "failed to convert"); // deduced std::string wstring s = boost::convert::to<wstring>(-1); // explicit std::wstring type wstring s = boost::convert::to(-1, L"failed to convert"); // deduced std::wstring Can you meet me half-way? I'll "give" you the string namespace "back" and you get to keep "_string" as spare for something else... looks like you get two things :-)... in case I again embarassed myself with my English I am trying to be humorous here... but I really think it might be a good way forward. The code is pleasant to read (IMHO), it leaves plenty of room for growth (like convert::to<int, rounding::down>). I really like it. All the functionality above is already in place. All that is needed is to change the namespace and get rid of the redundant convert().
Although convert might allow mix-fix relatively nicely: convert("5").to<int>(), ...
It looks clever. However, with the default/failure parameter it will probably be int i = convert("5").to(-1); Now it looks confusing... to me. Somehow I feel more comfortable with the example further up. V.