PEP 820: PySlot: Unified slot system for the C API #4754
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skirpichev
reviewed
Dec 20, 2025
Co-authored-by: Sergey B Kirpichev <skirpichev@gmail.com>
`Py_slot_invalid` with OPTIONAL can be used as a no-op slot
AA-Turner
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Dec 23, 2025
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Couple of columns over 80 chars, could optionally reflow.
A
| change the details. | ||
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| Both structures contain a *slots* field – essentially an array of | ||
| `tagged unions <https://en.wikipedia.org/wiki/Tagged_union>`_, |
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| `tagged unions <https://en.wikipedia.org/wiki/Tagged_union>`_, | |
| `tagged unions <https://en.wikipedia.org/wiki/Tagged_union>`__, |
| Discussions-To: Pending | ||
| Status: Draft | ||
| Type: Standards Track | ||
| Created: 17-Dec-2025 |
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| Created: 17-Dec-2025 | |
| Created: 19-Dec-2025 |
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| PyObject *MyClass = PyType_FromSlots(myClass_slots, -1); |
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| ... | |
| PyObject *MyClass = PyType_FromSlots(myClass_slots, -1); | |
| // ... | |
| PyObject *MyClass = PyType_FromSlots(myClass_slots, -1); |
| - Non-pointers (``basicsize``, ``flags``). | ||
| Originally, slots were intended to | ||
| only contain *function pointers*; they now contain *data pointers* as well as | ||
| integers or flags. This proposal uses an union to handle types cleanly. |
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| integers or flags. This proposal uses an union to handle types cleanly. | |
| integers or flags. This proposal uses a union to handle types cleanly. |
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Basic requirements (all PEP Types)
pep-NNNN.rst), PR title (PEP 123: <Title of PEP>) andPEPheaderAuthororSponsor, and formally confirmed their approvalAuthor,Status(Draft),TypeandCreatedheaders filled out correctlyPEP-Delegate,Topic,RequiresandReplacesheaders completed if appropriate.github/CODEOWNERSfor the PEPStandards Track requirements
Python-Versionset to valid (pre-beta) future Python version, if relevantDiscussions-ToandPost-History📚 Documentation preview 📚: https://pep-previews--4754.org.readthedocs.build/