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GeezerVison is showing github.com — gh-89519: Remove classmethod descriptor chaining, deprecated since 3.11 by rhettinger · Pull Request #110163 · python/cpython

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rhettinger commented Sep 30, 2023 •

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Issue: Calling help executes @classmethod @property decorated methods #89519

📚 Documentation preview 📚: https://cpython-previews--110163.org.readthedocs.build/

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          pythongh-89519: Remove classmethod descriptor chaining, deprecated si…

1f9686f

…nce 3.11

rhettinger added type-bug

An unexpected behavior, bug, or error

3.13 only security fixes labels

Sep 30, 2023

bedevere-app Bot added the awaiting review label

Sep 30, 2023

bedevere-app Bot mentioned this pull request

Sep 30, 2023

Calling help executes @classmethod @property decorated methods #89519

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rhettinger added 2 commits

September 30, 2023 17:30


          Add blurb

340d20f


          Remove doctests for classmethod descriptor chaining

155fdf2

rhettinger commented Oct 1, 2023

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I'm still working on the doctest for the descriptor howto. It looks like the classmethod emulation is imperfect after the classproperty has been removed.

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rhettinger and others added 2 commits

October 2, 2023 11:40


          Complete the emulation of MethodType.

8336eb0


          Merge branch 'main' into remove_classmethod_descriptor_chaining

a7b0830

KevinMGranger commented Oct 23, 2023

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Will this break the pattern described as an alternative to abc.abstractclassmethod?

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rhettinger commented Oct 24, 2023

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@KevinMGranger The examples for combining abstractmethod with classmethod and staticmethod will still work. This is tested in test_abstractclassmethod_basics() in Lib/test/test_abc. Also, here's a live demonstration:

% ./python.exe
Python 3.13.0a0 (heads/remove_classmethod_descriptor_chaining:8336eb0b87, Oct 24 2023, 14:41:05) [Clang 15.0.0 (clang-1500.0.40.1)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from abc import ABC, abstractmethod
>>> class C(ABC):
...     @classmethod
...     @abstractmethod
...     def my_abstract_classmethod(cls, arg):
...         ...
...
>>> C()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: Can't instantiate abstract class C without an implementation for abstract method 'my_abstract_classmethod'

Note, these examples have worked since Python 3.3 which was long before the broken descriptor chaining arrived in Python 3.9. So, they are independent of the change being reverted. Thanks for asking.

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facebook-github-bot pushed a commit to facebookincubator/MetaPython that referenced this pull request

Oct 25, 2023


          GH-89519: Remove classmethod descriptor chaining, deprecated since 3.…

6f02c7f

…11 (#110163)

Summary: backporting [Raymond Hettinger's `remove_classmethod_descriptor_chaining` branch](https://github.com/rhettinger/cpython/tree/remove_classmethod_descriptor_chaining) (pending upstream PR [GH-110163](python/cpython#110163)), part of upstream issue [GH-89519](python/cpython#89519)

Reviewed By: swtaarrs

Differential Revision: D50534886

fbshipit-source-id: 05b29193ce220f0d91fd0df8d5cef34d7e923456

itamaro commented Oct 26, 2023

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Looking forward to see this getting merged!

fwiw, I ran into an issue related to classmethod descriptor chaining in the Meta codebase -- some code (that was written for Python 3.8, doing a bunch of signature and type inspection of decorated methods) started breaking under Python 3.10.
I backported the deprecation from 3.11 and this removal into Cinder 3.10, and it resolved the issue.

If it helps with confidence in the removal - this PR (cleanly backported to 3.10) is running in production (in Instagram and other Meta Python services), after all internal test suites passed (including the full Instagram test suite).

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rhettinger commented Oct 27, 2023

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@itamaro Thank you for your comment. Indeed, it does increase the confidence in the PR.

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          Merge branch 'main' into remove_classmethod_descriptor_chaining

291ed52

rhettinger added the 🔨 test-with-buildbots Test PR w/ buildbots; report in status section label

Oct 27, 2023

bedevere-bot commented Oct 27, 2023

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🤖 New build scheduled with the buildbot fleet by @rhettinger for commit 291ed52 🤖

If you want to schedule another build, you need to add the 🔨 test-with-buildbots label again.

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bedevere-bot removed the 🔨 test-with-buildbots Test PR w/ buildbots; report in status section label

Oct 27, 2023

rhettinger merged commit 7f9a99e into python:main

Oct 27, 2023

bedevere-app Bot removed the awaiting review label

Oct 27, 2023

rhettinger deleted the remove_classmethod_descriptor_chaining branch

October 27, 2023 05:25

facebook-github-bot pushed a commit to facebookincubator/MetaPython that referenced this pull request

Dec 22, 2023


          gh-89519 & gh-113157 (Remove classmethod descriptor chaining, depreca…

f508768

…ted since 3.11)

Summary:
backport upstream PRs python/cpython#110163 and python/cpython#113233

upstream issues: python/cpython#89519 (Calling help executes classmethod property decorated methods) and python/cpython#113157 (Changed behavior of <instancemethod>.__get__ in Python 3.11)

upstream commits: [`7f9a99e8549b792662f2cd28bf38a4d4625bd402`](python/cpython@7f9a99e) and [`d058eaeed44766a8291013b275ad22f153935d3b`](python/cpython@d058eae)

Reviewed By: aleivag

Differential Revision: D52014322

fbshipit-source-id: 87de6d9587bd9cc49f053ca340adfc469b041f91

aisk pushed a commit to aisk/cpython that referenced this pull request

Feb 11, 2024


          pythongh-89519: Remove classmethod descriptor chaining, deprecated si…

c63736d

…nce 3.11 (pythongh-110163)

0Hughman0 mentioned this pull request

Jul 9, 2024

CachedClassProps and CachedProp really don't play well with any tooling. 0Hughman0/Cassini#86

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Glyphack pushed a commit to Glyphack/cpython that referenced this pull request

Sep 2, 2024


          pythongh-89519: Remove classmethod descriptor chaining, deprecated si…

e3d33d5

…nce 3.11 (pythongh-110163)

chrisimcevoy mentioned this pull request

Sep 20, 2025

PyCharm gets confused about metaclass properties chrisimcevoy/pyoda-time#159

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copybara-service Bot pushed a commit to google/fiddle that referenced this pull request

Jan 12, 2026


          Prepare for Python 3.13: replace classmethod(AutoConfig(...)) with …

1b9fda6

…a new dedicated `AutoConfigClassMethod` descriptor.

This is necessary because Python 3.13 no longer recognizes descriptor chaining: python/cpython#110163

PiperOrigin-RevId: 855235679

copybara-service Bot mentioned this pull request

Jan 12, 2026

Prepare for Python 3.13: replace classmethod(AutoConfig(...)) with a new dedicated AutoConfigClassMethod descriptor. google/fiddle#598

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copybara-service Bot pushed a commit to google/fiddle that referenced this pull request

Jan 12, 2026


          Prepare for Python 3.13: replace classmethod(AutoConfig(...)) with …

67c2eb6

…a new dedicated `AutoConfigClassMethod` descriptor.

This is necessary because Python 3.13 no longer recognizes descriptor chaining: python/cpython#110163

PiperOrigin-RevId: 855235679

copybara-service Bot pushed a commit to google/fiddle that referenced this pull request

Jan 13, 2026


          Prepare for Python 3.13: replace classmethod(AutoConfig(...)) with …

01c6891

…a new dedicated `AutoConfigClassMethod` descriptor.

This is necessary because Python 3.13 no longer recognizes descriptor chaining: python/cpython#110163

PiperOrigin-RevId: 855235679

copybara-service Bot pushed a commit to google/fiddle that referenced this pull request

Jan 13, 2026


          Prepare for Python 3.13: replace classmethod(AutoConfig(...)) with …

803ea8e

…a new dedicated `AutoConfigClassMethod` descriptor.

This is necessary because Python 3.13 no longer recognizes descriptor chaining: python/cpython#110163

PiperOrigin-RevId: 855235679

copybara-service Bot pushed a commit to google/fiddle that referenced this pull request

Jan 15, 2026


          Prepare for Python 3.13: replace classmethod(AutoConfig(...)) with …

1f05ce1

…a new dedicated `AutoConfigClassMethod` descriptor.

This is necessary because Python 3.13 no longer recognizes descriptor chaining: python/cpython#110163

PiperOrigin-RevId: 855235679

copybara-service Bot pushed a commit to google/fiddle that referenced this pull request

Jan 15, 2026


          Prepare for Python 3.13: replace classmethod(AutoConfig(...)) with …

f459007

…a new dedicated `AutoConfigClassMethod` descriptor.

This is necessary because Python 3.13 no longer recognizes descriptor chaining: python/cpython#110163

PiperOrigin-RevId: 855235679

copybara-service Bot pushed a commit to google/fiddle that referenced this pull request

Jan 15, 2026


          Prepare for Python 3.13: replace classmethod(AutoConfig(...)) with …

3d956df

…a new dedicated `AutoConfigClassMethod` descriptor.

This is necessary because Python 3.13 no longer recognizes descriptor chaining: python/cpython#110163

PiperOrigin-RevId: 856608179

ambv mentioned this pull request

Oct 20, 2026

gh-89519: Emit a warning when classmethod() wraps a non-callable descriptor #92426

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rhettinger commented Sep 30, 2023 •

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