[Python-Dev] RFC: PEP 509: Add a private version to dict (original) (raw)

Antoine Pitrou antoine at python.org
Fri Apr 15 05:01:00 EDT 2016

Victor Stinner <victor.stinner gmail.com> writes:

Hi, 2016-04-14 22:42 GMT+02:00 Armin Rigo <arigo tunes.org>: > Hi Victor, > > On 14 April 2016 at 17:19, Victor Stinner <victor.stinner gmail.com> wrote: >> Each time a dictionary is created, the global >> version is incremented and the dictionary version is initialized to the >> global version. > > A detail, but why not set the version tag of new empty dictionaries to > zero, always? Same after a clear(). This would satisfy the > condition: equality of the version tag is supposed to mean "the > dictionary content is precisely the same". You're right that incrementing the global version is useless for these specific cases, and using the version 0 should work. It only matters that the version (version? version tag?) is different.

Why do this? It's a nice property that two dicts always have different version tags, and now you're killing this property for... no obvious reason?

Do you really think dict.clear() is in need of micro-optimizing a couple CPU cycles away?

Regards

Antoine.

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