Register multiprocessing proxy types to an appropriate collections.abc class

[tungol]

Feature or enhancement

Proposal:

For consistency with the types that they proxy, I believe that multiprocessing.managers.ListProxy should be registered to collections.abc.MutableSequence and multiprocessing.managers.DictProxy should be registered to collections.abc.MutableMapping. This could be done by registering either those types themselves or by registering their base classes, BaseListProxy and _BaseDictProxy.

Has this already been discussed elsewhere?

This is a minor feature, which does not need previous discussion elsewhere

Links to previous discussion of this feature:

I discovered that these weren't registered to their ABCs while working on typeshed, so a little previous discussion occurred in issues in that repo:

python/typeshed#12893

python/typeshed#12892

Linked PRs

• gh-126417: Register multiprocessing proxy types to an appropriate collections.abc class #126419
• [3.13] gh-126417: Register multiprocessing proxy types to an appropriate collections.abc class (#126419) #126435
• [3.12] gh-126417: Register multiprocessing proxy types to an appropriate collections.abc class (#126419) #126436
• gh-126417: validate ABC methods on multiprocessing proxy types #126454
• [3.13] gh-126417: validate ABC methods on multiprocessing proxy types (GH-126454) #126674
• [3.12] gh-126417: validate ABC methods on multiprocessing proxy types (GH-126454) #126675

[AlexWaygood]

Thanks @tungol!

[gpshead]

FYI - The backports of the validation test don't work on 3.13 or earlier because ListProxy in those versions does not have the methods added to 3.14 by #103133.

I'll close those backports.

[AlexWaygood]

The backports of the original PR are being reverted in:

• [3.13] gh-126451: Revert backports of ABC registrations for contextvars.Context and multiprocessing proxies #126734
• [3.12] gh-126451: Revert backports of ABC registrations for contextvars.Context and multiprocessing proxies #126735

(We're not reverting it for 3.14+, it's a good change! But there were concerns raised in #126451 over whether it was a good idea to backport this kind of change, and I think those concerns were reasonable.)