Re: [boost] Formal Review Request: Boost.String.Convert

Subject: Re: [boost] Formal Review Request: Boost.String.Convert
From: Vladimir Batov (batov_at_[hidden])
Date: 2009-02-16 23:30:28

Hartmut,

> Why not allow to convert between different string types?

Yes, I believe that is a very sensible question. In fact, I've tightened up 
the type checks for the implemented boost::string::convert()  to minimize 
possible signature clashes with/of  further extensions (via 
specializations/oveloads).

In the current form boost::string::convert() is essentially a replacement 
for lexical_cast with added forrmatting, locale, etc. support. To add, say, 
u8string<->wstring conversion support we'll need overloads

        std::wstring convert(std::u8string)
        std::u8string convert(std::wstring)

added.

> Possible applications:
>
>  - std::string <--> std::wstring or similar (based on a future
> Boost.Unicode library)

I am not sure we can do std::string <-> std::wstring unless we know what 
std::string represents (currently it can be UTF8 or MBCS). If, with the 
introduction of std::u8string, std::string is guaranteed to be MBCS, then I 
guess we can have std::string <-> std::wstring as well.

>  - conversion between different symbol (character) sets

Currently convert() heavily relies on supplied types. Are we going to have 
distinct types for different symbol (character) sets? If not, then we might 
move forward as I've done for the throwing behavior (i.e. run-time 
configuration vs. compile-time configuration):

int i = boost::string::convert(str, -1) >> boost::throw_t();

to pass a clue/directive what to do. Similarly we might do

string new_set_str = boost::string::convert(old_set_str) >> 
new_set_directive();

Just thinking out loud. Does it look anywhere close to what you had in mind?

V.

P.S. Thank you for your Spirit conversion snippet another day. Appreciated.