Description

encukou

opened on Oct 24, 2025

Issue body actions

Feature or enhancement

Proposal:

See PEP 793. I'll copy the abstract for reference:

In this PEP, we propose a new entry point for C extension modules, by which one can define a module using an array of PyModuleDef_Slot structures without an enclosing PyModuleDef structure. This allows extension authors to avoid using a statically allocated PyObject, lifting the most common obstacle to making one compiled library file usable with both regular and free-threaded builds of CPython.

To make this viable, we also specify new module slot types to replace PyModuleDef’s fields, and to allow adding a token similar to the Py_tp_token used for type objects.

We also add an API for defining modules from slots dynamically.

The existing API (PyInit_*) is soft-deprecated. (That is: it will continue to work without warnings, and it’ll be fully documented and supported, but we plan to not add any new features to it.)

---

• Initial implementation (gh-140550: Initial implementation of PEP 793 – PyModExport #140556)
• Docs:
  • Reference docs (gh-140550: PEP 793 reference documentation #141197)
    • Soft-deprecate PyInit_* (gh-140550: PEP 793 reference documentation #141197)
    • Better explanation of module state (gh-140550: PEP 793 reference documentation #141197)
    • Give an example for tokens (gh-140550: PEP 793 reference documentation #141197)
  • What's New
    • a notice for DYNLOADFILE users? (edit: This shouldn't have changed/broken more than usual.)
  • Porting guide HOWTO
    • Document that the export hook runs without GIL in FT builds (see #141780) (gh-140550: Docs notes for PEP 793 #151661)
  • Tutorial update (gh-134160: Start "Extending and embedding" with a Diataxis-style tutorial #142314)
  • Mentions in PyImport_AppendInittab & friends (gh-140550: Docs notes for PEP 793 #151661)
  • Make sure references to new API are linked:
    • PyMod_Execin PyImport_CreateModuleFromInitfunc docs is linked (gh-140550: PEP 793 reference documentation #141197)
    • PyMODEXPORT_FUNC in blurb for #141672
    • blurb for #141780
• xxlimited.c update (gh-140550: Update xxlimited with 3.15 limited API & PEP 697 #142827)
  • Remove/replace _Py_OPAQUE_PYOBJECT in xxlimited.c (by 3.15.0 beta)

Optional stretch goals:

• Remove the PyInit function from Lib/test/test_cext/extension.c (gh-140550: Remove PyInit function from test_cext #141511)
• Speed & size improvements
  • importdl: load the DLL once
  • bool for the GIL flag (gh-140550: Use a bool for the Py_mod_gil value #141519)
• No longer require spec.name in PyModule_FromSlotsAndSpec
• No longer require static allocation for Py_mod_methods
• Add a PyModule_GetStateWithToken() function

Has this already been discussed elsewhere?

No response given

Links to previous discussion of this feature:

No response

Linked PRs

• gh-140550: Initial implementation of PEP 793 – PyModExport #140556
• gh-140550: Run make regen-limited-abi #141056
• gh-140550: PEP 793 reference documentation #141197
• gh-140550: Remove PyInit function from test_cext #141511
• gh-140550: Use a bool for the Py_mod_gil value #141519
• gh-140550: Correct error message for PyModExport (PEP 793) hook #142583
• gh-140550: Update xxlimited with 3.15 limited API & PEP 697 #142827
• gh-140550: allow slots that repeat information from PyModuleDef #144340
• gh-140550: Single What's New highlight for PEPs 793, 803 and 820 #149397
• [3.15] gh-140550: Update xxlimited with 3.15 limited API (GH-142827) #149785
• gh-140550: Docs notes for PEP 793 #151661
• [3.15] gh-140550: Docs additions & fixups for PEP 793 (GH-151661) #152064
• gh-140550: Enable limited C API tests on Free Threading in test_cext #157493
• [3.15] gh-140550: Fix PyABIInfo_VAR macro: avoid ";" #157494
• gh-140550: Fix PyABIInfo_VAR macro: avoid ";" #157539
• [3.15] gh-140550: Enable limited C API tests on Free Threading in test_cext (GH-157493) #157560

See also:

• gh-141671: PyMODINIT_FUNC: apply __declspec(dllexport) on Windows #141672
• gh-134160: Start "Extending and embedding" with a Diataxis-style tutorial #142314

Reacted by Tan Long and Peter Bierma

Reacted by Stan Ulbrych and Peter Bierma

Reacted by Bartosz Sławecki

Activity

1. encukou

   added

   type-featureA feature request or enhancementA feature request or enhancement

   on Oct 24, 2025
2. StanFromIreland

   added

   interpreter-core(Objects, Python, Grammar, and Parser dirs)(Objects, Python, Grammar, and Parser dirs)

   topic-C-API

   on Oct 24, 2025
3. encukou

   added a commit that references this issue on Nov 5, 2025

   gh-140550: Initial implementation of PEP 793 – PyModExport (GH-140556)

   589a03a
4. vstinner

   added 2 commits that reference this issue on Nov 5, 2025

   pythongh-140550: Run make regen-limited-abi

   dd03049

   gh-140550: Run make regen-limited-abi (#141056)

   579b2f8
5. encukou

   added 2 commits that reference this issue on Nov 7, 2025

   pythongh-140550: PEP 793 reference documentation

   0142b5d

   pythongh-140550: Removp PyInit function from test_cext

   1ad68bf
6. encukou commented on Nov 13, 2025

   

   encukou

   on Nov 13, 2025

   MemberAuthor

   More actions

   I'd appreciate a review of the reference docs update: #141197
7. encukou

   added 2 commits that reference this issue on Nov 13, 2025

   pythongh-140550: Use a bool for the Py_mod_gil value

   36dcf00

   gh-140550: Use a bool for the Py_mod_gil value (GH-141519)

   a4dd662
8. encukou

   added a commit that references this issue on Nov 26, 2025

   gh-140550: PEP 793 reference documentation (GH-141197)

   d7f0214
9. StanFromIreland

   added 3 commits that reference this issue on Dec 6, 2025

   pythongh-140550: Initial implementation of PEP 793 – PyModExport (pyt…

   7e30dee

   pythongh-140550: Run make regen-limited-abi (python#141056)

   2d83666

   pythongh-140550: Use a bool for the Py_mod_gil value (pythonGH-141519)

   ae32d26
10. 10 remaining items

11. davin-core commented on Mar 24, 2026

    

    davin-core

    on Mar 24, 2026

    More actions

    @encukou I am trying to update a library to include this feature in 3.15, and I am wondering if the PY_VERSION_HEX for this version is 0x030F0000. Does this version exist?
12. ljfp

    added a commit that references this issue on Apr 25, 2026

    pythongh-140550: allow slots that repeat information from PyModuleDef (…

    4c9469d
13. encukou

    added a commit that references this issue on May 5, 2026

    gh-140550: Single What's New highlight for PEPs 793, 803 and 820 (GH-…

    02d02f4
14. encukou

    added 2 commits that reference this issue on May 13, 2026

    gh-140550: Update xxlimited with 3.15 limited API (GH-142827)

    fa81cd9

    [3.15] gh-140550: Update xxlimited with 3.15 limited API (GH-142827) (G…

    b650305
15. encukou commented on Jun 18, 2026

    

    encukou

    on Jun 18, 2026

    MemberAuthor

    More actions

    @davin-core

    I am trying to update a library to include this feature in 3.15, and I am wondering if the PY_VERSION_HEX for this version is 0x030F0000. Does this version exist?

    Sorry, I missed the notification.

    To use wording in the docs: 0x030F0000 does not correspond to any Python release, but is useful in numeric comparisons.

    You can use 0x030F0000 to mean "3.15+" in e.g.:

    • PY_VERSION_HEX >= 0x030F0000
    • #define Py_LIMITED_API 0x030F0000
    • #define Py_TARGET_ABI3T 0x030F0000
16. encukou

    added 2 commits that reference this issue on Jun 24, 2026

    gh-140550: Docs additions & fixups for PEP 793 (GH-151661)

    763cc22

    [3.15] gh-140550: Docs additions & fixups for PEP 793 (GH-151661) (GH…

    bc52a01
17. vstinner

    added 2 commits that reference this issue on Sep 14, 2026

    pythongh-140550: Enable limited C API tests on Free Threading in test…

    3e76111

    pythongh-140550: Enable limited C API tests on Free Threading in test…

    9bed8d3
18. encukou

    added a commit that references this issue on Sep 15, 2026

    pythongh-140550: Fix PyABIInfo_VAR macro: avoid ";"

    9435e20
19. hugovk

    added 2 commits that reference this issue on Sep 15, 2026

    gh-140550: Fix PyABIInfo_VAR macro: avoid ";" (#157539)

    cbb43b8

    [3.15] gh-140550: Fix PyABIInfo_VAR macro: avoid ";" (#157494)

    4b6de96
20. vstinner

    added a commit that references this issue on Sep 15, 2026

    gh-140550: Enable limited C API tests on Free Threading in test_cext (#…

    fb123c8
21. serhiy-storchaka

    added a commit that references this issue on Oct 10, 2026

    [3.15] gh-140550: Enable limited C API tests on Free Threading in tes…

    96f7177

Issue actions