[Python-Dev] Backporting PEP 3101 to 2.6

[Eric Smith]

Nick Coghlan wrote:
> Guido van Rossum wrote:
>> For data types whose output uses only ASCII, would it be acceptable if
>> they always returned an 8-bit string and left it up to the caller to
>> convert it to Unicode? This would apply to all numeric types. (The
>> date/time types have a strftime() style API which means the user must
>> be able to specifiy Unicode.)
> 
> To elaborate on this a bit (and handwaving a lot of important details 
> out of the way) do you mean something like the following for the builtin 
> format?:
> 
> def format(obj, fmt_spec=None):
>     if fmt_spec is None: fmt_spec=''
>     result = obj.__format__(fmt_spec)
>     if isinstance(fmt_spec, unicode):
>         if isinstance(result, str):
>             result = unicode(result)
>     return result

That's the approach I'm taking.  The builtin format is the only caller 
of __format__ that I know of, so it's the only place this would need to 
be done.