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gh-47146: Soft-deprecate structmember.h, expose its contents via Python.h by encukou · Pull Request #99014 · python/cpython

encukou

The structmember.h header is deprecated, though it continues to be available and there are no plans to remove it. There are no deprecation warnings. Old code can stay unchanged (unless the extra include and non-namespaced macros bother you greatly). Specifically, no uses in CPython are updated -- that would just be unnecessary churn.

The header's contents are now available just by including Python.h, with a PY_ prefix added if it was missing:

  • PyMemberDef, PyMember_GetOne, PyMember_SetOne
  • Type macros like PY_T_INT, PY_T_DOUBLE, etc. (previously T_INT, T_DOUBLE, etc.)
  • The flags PY_READONLY (previously READONLY) and PY_AUDIT_READ (name unchanged)

Several items are not exposed from Python.h:

  • T_OBJECT (use PY_T_OBJECT_EX)
  • T_NONE (previously undocumented, and pretty quirky)
  • The macro WRITE_RESTRICTED which does nothing.
  • The macros RESTRICTED and READ_RESTRICTED, equivalents of PY_AUDIT_READ.
  • In some configurations, <stddef.h> is not included from Python.h.
    It should be included manually when using offsetof().

The PY_T_*, PY_READONLY and PY_AUDIT_READ macros are added to the stable API manifest. This is just a clerical change, really -- Stable ABI extensions in the wild use structmember.h, and PyMemberDef & Py_tp_members are already listed.

There is discussion on the issue to rename T_PYSSIZET to PY_T_SSIZE or similar. I chose not to do that -- users will probably copy/paste that with any spelling, and not renaming it makes migration docs simpler.

Co-Authored-By: Alexander Belopolsky abalkin@users.noreply.github.com
Co-Authored-By: Matthias Braun MatzeB@users.noreply.github.com