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

Wed Nov 14 19:12:25 CET 2012

On 2012年11月14日, at 18:10 , Mark Adam wrote:
>> Try the canonical {'x':1}. Only dict allows the special
> initialization above. Other collections require an iterable.

Other collections don't have a choice, because it would often be
ambiguous. Dicts do not have that issue.
> I'm guessing
> **kwargs initialization was only used because it is so simple to
> implement, but that's not necessarily a heuristic for good language design.

In this case it very much is, it permits easily merging two dicts in a
single expression or cloning-with-replacement. It also mirrors the
signature of dict.update which I think is a Good Thing.