Stefan Seefeld <seefeld@[...].ca>  writes:

>  David Abrahams wrote:
> > "Lijun Qin" <qinlj@[...].com> writes:
> > 
> >>Hi all,
> >>
> >>I'm using boost.python to wrap the WTL (Windows Template Libaray), using VC
> >>7.1 and porting some old code previously use win32ui.pyd.
> >>Basically it is easy to do, though gccxml failed to parse the ATL/WTL code
> >>so I can not use Pyste.
> >>But there is a trouble, does anybody know how to automaticly convert
> >>PyUnicode to 'const char *'? Without this, I have to change lot of code
> >>lines to explictly use str() function.
> > I'm not an expert in it, but I thought Unicode used 16- or 32- byte
> > wchar_t characters.  How would you convert it to char const*?
> 
>  unicode allows different encodings, some (such as utf-8) with variably
>  sized character representations. This means that conversions usually
>  can't be done on-the-fly without helper constructs, i.e. some memory
>  management is needed.
> 
>  As an example, I'm doing such conversions in a xml library. The C
>  implementation uses 'xmlChar *', which is just an alias for 'char *',
>  but really holds utf-8 encoded text.
>  I convert it to various string types (the public API is parametrized
>  for the string type):

To do that kind of narrowing, at the moment, the only way would be to
write a thin wrapper function:
      
      void f(char const*);
 
      void f_thin_wrapper(object unicode)
      {
          str narrowed(unicode);
          f(extract<char const*> (str));
      }

we may have some support for doing this automatically in the version
of Boost.Python which integrates with Luabind, but that's a ways off
yet.

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com


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