Implement PEP 793 – PyModExport

[encukou]

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.)

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• 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
    • Give an example for tokens
  • What's New
  • Porting guide HOWTO
  • Tutorial update
• xxlimited.c update
• Remove the PyInit function from Lib/test/test_cext/extension.c

Optional stretch goals:

• Speed & size improvements
• 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