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PEP 573: Module State Access from C Extension Methods #82968

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Closed
PEP 573: Module State Access from C Extension Methods#82968
Labels
3.9 (EOL)end of lifeextension-modulesC modules in the Modules dirtype-featureA feature request or enhancement

Description

@Dormouse759
Dormouse759
mannequin
opened on Nov 13, 2019
BPO 38787
Nosy @terryjreedy, @ncoghlan, @scoder, @vstinner, @encukou, @Dormouse759, @miss-islington, @shihai1991
PRs
  • [PEP 573] bpo-38787: Module State Access from C Extension Methods #17145
  • bpo-38787: C API for module state access from extension methods (PEP 573) #19936
  • bpo-38787: update docs of structures.rst and code style of _testmultiphase.c #19980
  • bpo-38787: Add PyCFunction_CheckExact() macro for exact type checks #20024
  • bpo-38787: Fix Argument Clinic defining_class_converter #20074
  • bpo-38787: Clarify docs for PyType_GetModule and warn against common mistake #20215
  • Remove a redundant NULL in descrobject.c #20344
  • [3.9] bpo-38787: Clarify docs for PyType_GetModule and warn against common mistake (GH-20215) #21984
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    Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.

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    GitHub fields:

    assignee = None
closed_at = <Date 2020-10-20.08:56:18.304>
created_at = <Date 2019-11-13.14:30:40.496>
labels = ['extension-modules', 'type-feature', '3.9']
title = 'PEP 573: Module State Access from C Extension Methods'
updated_at = <Date 2020-11-25.17:08:25.229>
user = 'https://github.com/Dormouse759'

    bugs.python.org fields:

    activity = <Date 2020-11-25.17:08:25.229>
actor = 'vstinner'
assignee = 'none'
closed = True
closed_date = <Date 2020-10-20.08:56:18.304>
closer = 'petr.viktorin'
components = ['Extension Modules']
creation = <Date 2019-11-13.14:30:40.496>
creator = 'Dormouse759'
dependencies = []
files = []
hgrepos = []
issue_num = 38787
keywords = ['patch']
message_count = 18.0
messages = ['356533', '367552', '367569', '367636', '368180', '368337', '368356', '368577', '368580', '368733', '368735', '368768', '368789', '368804', '375991', '376411', '379107', '381853']
nosy_count = 8.0
nosy_names = ['terry.reedy', 'ncoghlan', 'scoder', 'vstinner', 'petr.viktorin', 'Dormouse759', 'miss-islington', 'shihai1991']
pr_nums = ['17145', '19936', '19980', '20024', '20074', '20215', '20344', '21984']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue38787'
versions = ['Python 3.9']

    Activity

    1. Dormouse759 commented on Nov 13, 2019

      @Dormouse759
      Dormouse759mannequin
      on Nov 13, 2019
      MannequinAuthor

      Currently, there is not way to access per-module state from the methods of types defined in extension modules.

      This PEP provides a fix to this issue.

      PEP-573 - https://www.python.org/dev/peps/pep-0573/

      Reference implementation - https://github.com/Dormouse759/cpython/tree/pep-c-rebase_newer

    2. Dormouse759
      added
      3.9 (EOL)end of life
      extension-modulesC modules in the Modules dir
      type-featureA feature request or enhancement
      on Nov 13, 2019

    3. scoder commented on Apr 28, 2020

      @scoder
      scoder
      on Apr 28, 2020
      Contributor

      What can we do to move this forward? I see that the original PR was closed in January. Is there or will there be a new one? Can I help with anything?

    4. terryjreedy commented on Apr 28, 2020

      @terryjreedy
      terryjreedy
      on Apr 28, 2020
      Member

      The PEP is listed as accepted, with you as the BDFL-delegate, but it lacks a link to the public acceptance message (usually on pydev list).

      The PR was not rejected by a core dev but was closed without explanation by the author on the same day the last commits were added. Perhaps OP just gave up getting tests to pass. But they disappear on closes.

      However, the contribution had been made under the CLA and you or Petr or any other core dev should be able to download it to a local branch, try to whip it into shape, and make a new PR before beta 1, in about a month. Or start from scratch.

      I cannot test downloading at the moment. Apparently, OP's fork branch has been altered, so that merely reopening is not an option. The OP used force-pushes rather than update merges, and this often creates problems.

    5. encukou commented on Apr 29, 2020

      @encukou
      encukou
      on Apr 29, 2020
      Member

      I'm working on the implementation as my time allows, here: encukou#3 .

      Would it help to create a proper PR for CPython now? That would mean I could no longer do rebases/force-pushes, so the commits would be less readable. But happy to do it if it would help you.

    6. vstinner commented on May 5, 2020

      @vstinner
      vstinner
      on May 5, 2020
      Member

      See also bpo-40137: TODO list when PEP-573 "Module State Access from C Extension Methods" will be implemented.

    7. vstinner commented on May 7, 2020

      @vstinner
      vstinner
      on May 7, 2020
      Member

      New changeset e1becf4 by Petr Viktorin in branch 'master':
      bpo-38787: C API for module state access from extension methods (PEP-573) (GH-19936)
      e1becf4

    8. vstinner commented on May 7, 2020

      @vstinner
      vstinner
      on May 7, 2020
      Member

      New changeset c068b53 by Hai Shi in branch 'master':
      bpo-38787: Update structures.rst docs (PEP-573) (GH-19980)
      c068b53

    9. vstinner commented on May 10, 2020

      @vstinner
      vstinner
      on May 10, 2020
      Member

      See also bpo-40574: segfault causing regression from PEP-573 implementation (PyQt5).

    10. vstinner commented on May 10, 2020

      @vstinner
      vstinner
      on May 10, 2020
      Member

      The posix/nt and _abc modules now use the PEP-573 APIs:

    11. miss-islington commented on May 12, 2020

      @miss-islington
      miss-islington
      on May 12, 2020
      Contributor

      New changeset 4c9ea09 by scoder in branch 'master':
      bpo-38787: Add PyCFunction_CheckExact() macro for exact type checks (GH-20024)
      4c9ea09

    12. shihai1991 commented on May 12, 2020

      @shihai1991
      shihai1991
      on May 12, 2020
      Member

      In PR19982, petr have mentioned that PyType_GetModule can not worked if the type is the subtype.

      I try to use PEP-573 in functools, I get the error info from testcases:
      ======================================================================
      ERROR: test_arg_combinations (test.test_functools.TestPartialCSubclass)
      ----------------------------------------------------------------------

      Traceback (most recent call last):
  File "/temp/shihai/cpython/Lib/test/test_functools.py", line 109, in test_arg_combinations
    p = self.partial(capture)
TypeError: PyType_GetModule: Type 'CPartialSubclass' has no associated module

      ======================================================================
      ERROR: test_attributes (test.test_functools.TestPartialCSubclass)
      ----------------------------------------------------------------------

      Traceback (most recent call last):
  File "/temp/shihai/cpython/Lib/test/test_functools.py", line 71, in test_attributes
    p = self.partial(capture, 1, 2, a=10, b=20)
TypeError: PyType_GetModule: Type 'CPartialSubclass' has no associated module

    13. encukou commented on May 13, 2020

      @encukou
      encukou
      on May 13, 2020
      Member

      I guess I'll need to clarify the documentation here.
      Call PyType_GetModule on the defining class, not on type(self). See the PEP for details.
      The associated module is not inherited; each class in the MRO can be defined in a different module.

    14. shihai1991 commented on May 13, 2020

      @shihai1991
      shihai1991
      on May 13, 2020
      Member

      I guess I'll need to clarify the documentation here.
      Call PyType_GetModule on the defining class, not on type(self).

      +1, I didn't notice this detail until I got the error.

      The associated module is not inherited; each class in the MRO can be > defined in a different module.

      Thanks, pep have enough info, I need spend sometime to make sure I understand it clearly, Lol~.

    15. vstinner commented on May 13, 2020

      @vstinner
      vstinner
      on May 13, 2020
      Member

      New changeset 97e1568 by Victor Stinner in branch 'master':
      bpo-38787: Fix Argument Clinic defining_class_converter (GH-20074)
      97e1568

    16. encukou commented on Aug 27, 2020

      @encukou
      encukou
      on Aug 27, 2020
      Member

      New changeset d9a966a by Petr Viktorin in branch 'master':
      bpo-38787: Clarify docs for PyType_GetModule and warn against common mistake (GH-20215)
      d9a966a

    17. miss-islington commented on Sep 4, 2020

      @miss-islington
      miss-islington
      on Sep 4, 2020
      Contributor

      New changeset fbb9ee0 by Miss Islington (bot) in branch '3.9':
      [3.9] bpo-38787: Clarify docs for PyType_GetModule and warn against common mistake (GH-20215) (GH-21984)
      fbb9ee0

    18. encukou commented on Oct 20, 2020

      @encukou
      encukou
      on Oct 20, 2020
      Member

      Thanks Victor, Hai Shi, Pablo, Stefan, Dong-hee Na and Mariatta for reviews!

      I did not put all the details in the documentation because there are still feature gaps. So, a full write-up is now in the informational PEP-630.

    19. encukou
      closed this as completedon Oct 20, 2020

    20. vstinner commented on Nov 25, 2020

      @vstinner
      vstinner
      on Nov 25, 2020
      Member

      FYI Cython doesn't support this PEP yet: cython/cython#3917

    21. ezio-melotti
      transferred this issue fromon Apr 10, 2022
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