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

Xavier Morel catch-all at masklinn.net
Wed Nov 14 19:12:25 CET 2012

On 2012-11-14, 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.

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