GH-95589: Dont crash when subclassing extension classes with multiple inheritance #96028
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Doc/whatsnew/3.12.rst
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| :const:`Py_TPFLAGS_MANAGED_WEAKREF` instead of ``tp_dictoffset`` and | ||
| ``tp_weaklistoffset``, respectively. | ||
| The use of ``tp_dictoffset`` and ``tp_weaklistoffset`` is still | ||
| supported, but will not fully support multiple inheritance |
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| supported, but will not fully support multiple inheritance | |
| supported, but does not fully support multiple inheritance |
I was a little surprised by the tense here, but I also may be wrong.
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You are right.
Because this doesn't apply right now, I unthinkingly use the future tense.
| pass | ||
| class B2(Both1, cls): | ||
| class B2(C4, cls): | ||
| pass |
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Should we also assert that the mro of these classes looks correct?
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This won't change the mro. That's determined by the C3 algorithm. https://en.wikipedia.org/wiki/C3_linearization
| Classes declaring :const:`Py_TPFLAGS_MANAGED_DICT` should call | ||
| :c:func:`_PyObject_VisitManagedDict` and :c:func:`_PyObject_ClearManagedDict` | ||
| to traverse and clear their instance's dictionaries. | ||
| To clear weakrefs, call :c:func:`PyObject_ClearWeakRefs`, as before. |
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Should the extension docs be updated to provide examples of using the new API? (Probably as a separate PR...)
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Yes, they should. I also plan to add a new file documenting the new object layout.
Py_TPFLAGS_MANAGED_DICTandPy_TPFLAGS_MANAGED_WEAKREFtp_dictoffsetin inheritance. #95589