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Implement PEP 793 – PyModExport #140550
Description
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
- Reference docs (gh-140550: PEP 793 reference documentation #141197)
- 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:
Activity
gh-140550: Initial implementation of PEP 793 – PyModExport (GH-140556)
pythongh-140550: Run make regen-limited-abi
gh-140550: Run make regen-limited-abi (#141056)
pythongh-140550: PEP 793 reference documentation
pythongh-140550: Removp PyInit function from test_cext
encukou commented on Nov 13, 2025
I'd appreciate a review of the reference docs update: #141197
pythongh-140550: Use a bool for the Py_mod_gil value
gh-140550: Use a bool for the Py_mod_gil value (GH-141519)
gh-140550: PEP 793 reference documentation (GH-141197)
pythongh-140550: Initial implementation of PEP 793 – PyModExport (pyt…
pythongh-140550: Run make regen-limited-abi (python#141056)
pythongh-140550: Use a bool for the Py_mod_gil value (pythonGH-141519)
10 remaining items
davin-core commented on Mar 24, 2026
@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?
pythongh-140550: allow slots that repeat information from PyModuleDef (…
gh-140550: Single What's New highlight for PEPs 793, 803 and 820 (GH-…
gh-140550: Update xxlimited with 3.15 limited API (GH-142827)
[3.15] gh-140550: Update xxlimited with 3.15 limited API (GH-142827) (G…
encukou commented on Jun 18, 2026
@davin-core
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.:
gh-140550: Docs additions & fixups for PEP 793 (GH-151661)
[3.15] gh-140550: Docs additions & fixups for PEP 793 (GH-151661) (GH…
pythongh-140550: Enable limited C API tests on Free Threading in test…
pythongh-140550: Enable limited C API tests on Free Threading in test…
pythongh-140550: Fix PyABIInfo_VAR macro: avoid ";"
gh-140550: Fix PyABIInfo_VAR macro: avoid ";" (#157539)
[3.15] gh-140550: Fix PyABIInfo_VAR macro: avoid ";" (#157494)
gh-140550: Enable limited C API tests on Free Threading in test_cext (#…
[3.15] gh-140550: Enable limited C API tests on Free Threading in tes…