[Python-Dev] Backporting PEP 3101 to 2.6

[Steve Holden]

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
> 
Isn't unicode idempotent? Couldn't

          if isinstance(result, str):
              result = unicode(result)


avoid repeating in Python a test already made in C by re-spelling it as

         result = unicode(result)

or have you hand-waved away important details that mean the test really 
is required?

regards
  Steve
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