[Python-ideas] Allow using ** twice

[yoav glazner]

On Jun 7, 2013 1:08 PM, "Serhiy Storchaka" <storchaka at gmail.com> wrote:
>
> 07.06.13 10:31, Steven D'Aprano написав(ла):
>
>> At this point, I'd begin to think of a built-in updated function. Here's
>> one possible implementation, slightly different from yours below:
>>
>> def updated(*mappings, **kw):
>>      new = {}
>>      for mapping in mappings + (kw,):
>>          new.update(mapping)
>>      return new
>
>
> Or
>
> def updated(*mappings, **kw):
>     from collections import ChainMap
>     return ChainMap((kw,) + mappings[::-1])
>
>
>> Given how trivial is it, I'm not sure it's even worthwhile. But then,
>> prior to sorted and reversed being added as built-ins, people argued
>> that they were "too trivial" too. On the third hand, the existence of
>> two, or more, implementations with subtly different semantics is an
>> argument on picking the most useful version and putting it in the
>> standard library.
>>
>> So I'm now +0 for a built-in updated and +0.5 for collections.updated.
>
>
> I'm -1 for both. The collections module already contains an appropriate
tool. And if ChainMap() is not a builtin, why updated() should be?
>
ChainMap does not return a copy its a view
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