gh-140550: Initial implementation of PEP 793 – PyModExport #140556

encukou · 2025-10-24T16:18:03Z

This adds the initial implementation of PEP-793.
See the issue for follow-up tasks.

Issue: Implement PEP 793 – PyModExport #140550

This uses a "def-like" structure: a PyModuleDef* that's not a valid Python object.

Co-Authored-By: Victor Stinner <vstinner@python.org>

encukou

Thank you for the initial review!

Yes, but there's a lot of tests. And I've also renamed things that changed semantics, so unrelated changes/backports will conflict or fail to build, rather than merge cleanly at the Git level but be subtly broken.

encukou · 2025-10-28T17:16:50Z

Lib/test/test_capi/test_module.py

+import unittest
+import types


I couldn't find this in PEP 8.

Lib/test/test_sys.py

Modules/_testcapi/heaptype.c

Objects/moduleobject.c

encukou · 2025-10-28T17:37:57Z

!buildbot AMD64.FreeBSD.Refleaks

bedevere-bot · 2025-10-28T17:38:00Z

🤖 New build scheduled with the buildbot fleet by @encukou for commit 01d52ba 🤖

Results will be shown at:

https://buildbot.python.org/all/#/grid?branch=refs%2Fpull%2F140556%2Fmerge

The command will test the builders whose names match following regular expression: AMD64.FreeBSD.Refleaks

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AMD64 FreeBSD Refleaks PR

Objects/moduleobject.c

encukou · 2025-10-29T08:07:27Z

Do you plan to add documentation in a separated PR?

Yes. There's a lot to add since the PEP calls for soft-deprecation of PyInit_; see the issue.

Include/internal/pycore_moduleobject.h

Co-authored-by: Kumar Aditya <kumaraditya@python.org>

Python/import.c

vstinner

LGTM. Just please move _PyModule_GetGCHooks() to pycore_moduleobject.h.

vstinner · 2025-11-04T10:17:06Z

Include/internal/pycore_moduleobject.h

+static inline PyModuleDef *_PyModule_GetDefOrNull(PyObject *arg) {
+    PyModuleObject *mod = _PyModule_CAST(arg);
+    if (mod->md_token_is_def) {
+        return (PyModuleDef *)((PyModuleObject *)mod)->md_token;


Suggested change

return (PyModuleDef *)((PyModuleObject *)mod)->md_token;

return (PyModuleDef *)mod->md_token;

Include/moduleobject.h

vstinner · 2025-11-04T10:26:38Z

Lib/test/test_cext/extension.c


 PyMODINIT_FUNC
-FUNC_NAME(MODULE_NAME)(void)
+INITFUNC_NAME(MODULE_NAME)(void)


Is it really needed to define a PyInit function if a modexport function is defined with slots? Developers may reuse this code as an example.

Thanks for the catch! I think I had some platform-specific issues with the current version of setuptools. I added this to the TODO list in the issue; I'll get to it in a later PR.

Objects/moduleobject.c

encukou · 2025-11-05T11:31:18Z

Thank you for the review!

vstinner · 2025-11-05T12:59:01Z

Congrats :-)

vstinner · 2025-11-05T16:51:02Z

make check-limited-abi does now fail on the main branch:

./python -E ./Tools/build/generate-build-details.py `cat pybuilddir.txt`/build-details.json
Checked 115 modules (37 built-in, 77 shared, 1 n/a on linux-x86_64, 0 disabled, 0 missing, 0 failed on import)
./python ./Tools/build/stable_abi.py --all
File /home/vstinner/python/main/Doc/data/stable_abi.dat differs from expected!
--- /home/vstinner/python/main/Doc/data/stable_abi.dat
+++ <expected>
@@ -979,14 +979,6 @@
 type,Py_buffer,3.11,,full-abi
 type,Py_intptr_t,3.2,,
 macro,Py_mod_abi,3.15,,
-macro,Py_mod_doc,3.15,,
-macro,Py_mod_methods,3.15,,
-macro,Py_mod_name,3.15,,
-macro,Py_mod_state_clear,3.15,,
-macro,Py_mod_state_free,3.15,,
-macro,Py_mod_state_size,3.15,,
-macro,Py_mod_state_traverse,3.15,,
-macro,Py_mod_token,3.15,,
 macro,Py_mp_ass_subscript,3.2,,
 macro,Py_mp_length,3.2,,
 macro,Py_mp_subscript,3.2,,

I created #141056 to fix the issue.

encukou · 2025-11-05T17:02:20Z

Thank you!

encukou added 30 commits October 24, 2025 17:01

Define PyMODEXPORT_FUNC

4ad95be

Add new state to module object

c53650d

Make sure the module def matches the state

9564e20

Add simple test case

05a87c3

Add new slot definitions

57c4f1e

Modules are bigger sue me

956c59a

Add a test for PyModule_FromSlotsAndSpec

14a66d2

Add PyModule_FromSlotsAndSpec (empty for now)

72a27f5

Add module test

b54293b

Fill in enough of a PyModuleDef to pass to common machinery

fcc68f8

Pass in a spec

3ab607e

Rename field which can now be NULL

35d7d51

Common implementation for PyModule_From{Def,Slots}AndSpec

6fbbc18

This uses a "def-like" structure: a PyModuleDef* that's not a valid Python object.

Add test for Py_mod_name slot

7207e07

Handle Py_mod_name

8d4d264

Test repeated slot

bd61e5b

Test Py_mod_name with a def

d638abf

Py_mod_doc

b24e6a6

Disallow NULL slot value

756cbff

Test repeats and NULL for all new slots

320de14

Add PyModule_GetSize

4d88cf3

Test size

a1d3c15

Handle size

7fcee67

Test new slots with PyModuleDef

9fd1e7e

Py_mod_methods

fd95984

GC hooks

748e18f

Py_mod_token

1101f55

Py_mod_exec

488eae7

Clean up slot-handling a bit

f9d0dde

Py_mod_create

020dcc6

encukou and others added 2 commits October 28, 2025 18:30

PEP 7 whitespace

52af397

Make sure Victor's edits are credited

01d52ba

Co-Authored-By: Victor Stinner <vstinner@python.org>

encukou commented Oct 28, 2025

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vstinner reviewed Oct 28, 2025

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encukou added 2 commits October 29, 2025 09:02

Correct logic

ba6e602

Merge in the main branch

d26e9b7

kumaraditya303 reviewed Nov 2, 2025

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kumaraditya303 reviewed Nov 2, 2025

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encukou and others added 2 commits November 3, 2025 14:52

Get the spaces just right

26b57f2

Co-authored-by: Kumar Aditya <kumaraditya@python.org>

Merge branch 'main' into modexport-rebased

66e8309

kumaraditya303 reviewed Nov 3, 2025

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Python/import.c Outdated Show resolved Hide resolved

_PyModule_GetDefOrNull never raises

928f23b

vstinner approved these changes Nov 4, 2025

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bedevere-app bot added awaiting merge and removed awaiting core review labels Nov 4, 2025

encukou and others added 4 commits November 4, 2025 12:52

Merge in the main branch

4f3712f

Remove _PyModule_GetGCHooks; get the hooks directly via internal API

55ae793

Style fixes

1e6b18c

Remove unused variables

4d58846

encukou merged commit 589a03a into python:main Nov 5, 2025
46 checks passed

bedevere-app bot removed the awaiting merge label Nov 5, 2025

encukou deleted the modexport-rebased branch November 5, 2025 11:31

	return (PyModuleDef )((PyModuleObject )mod)->md_token;
	return (PyModuleDef *)mod->md_token;

		import unittest
		import types

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gh-140550: Initial implementation of PEP 793 – PyModExport #140556

gh-140550: Initial implementation of PEP 793 – PyModExport #140556

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encukou commented Oct 24, 2025 •

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