[Python-Dev] str.format_from_mapping

[Glenn Linderman]

On 10/31/2010 3:32 PM, Eric Smith wrote:
> On 10/31/2010 6:28 PM, Glenn Linderman wrote:
>> On 10/31/2010 2:02 PM, Benjamin Peterson wrote:
>>> 2010/10/31 Antoine Pitrou<solipsis at pitrou.net>:
>>>> >  On Sun, 31 Oct 2010 16:39:44 -0400
>>>> >  Eric Smith<eric at trueblade.com>  wrote:
>>>> >
>>>>> >>  What are your thoughts on adding a str.format_from_mapping (or 
>>>>> similar
>>>>> >>  name, maybe the suggested "format_map") to 3.2? See
>>>>> >> http://bugs.python.org/issue6081  . This method would be 
>>>>> similar to
>>>>> >>  "%(foo)s %(bar)s" % d, where d is a dict (or rather any 
>>>>> mapping object),
>>>>> >>  but of course would use str.format syntax: "{foo}
>>>>> >>  {bar}".format_from_mapping(d).
>>>> >
>>>> >  I must be missing something, but what's the difference with
>>>> >  XXX.format(**d)?
>>> It allows arbitrary mappings.
>>
>> Other than the language moratorium, why are arbitrary mappings not
>> allowed for the (**d) syntax?
>
> An arbitrary mapping would be converted to a dict.

Yes, but why convert?  I suppose it has something to do with the case 
where there are named parameters, in addition to a **kwargs formal, and 
the mixing and matching that happens as a result.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/python-dev/attachments/20101031/2251861c/attachment-0001.html>