[Python-Dev] performance of {} versus dict()

martin at v.loewis.de martin at v.loewis.de
Thu Nov 15 06:04:57 CET 2012

Zitat von Chris Angelico <rosuav at gmail.com>:

> On Thu, Nov 15, 2012 at 1:28 PM, Stephen J. Turnbull  
> <stephen at xemacs.org> wrote:
>> Chris Angelico writes:
>>  > >>> {"a":1}+{"b":2}
>>  > It would make sense for this to result in {"a":1,"b":2}.
>> The test is not "does this sometimes make sense?"  It's "does this
>> ever result in nonsense, and if so, do we care?"
>> Here, addition is usually commutative.  Should {'a':1}+{'a':2} be the
>> same as, or different from, {'a':2}+{'a':1}, or should it be an error?
>>>> "a"+"b"
> 'ab'
>>>> "b"+"a"
> 'ba'
> I would say that the two dictionary examples are equally allowed to
> give different results - that they should be equivalent to (shallow)
> copy followed by update(), but possibly more efficiently.

Can this be moved to python-ideas, please?


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