# PEP 820 – PySlot: Unified slot system for the C API

**URL:** <https://discuss.python.org/t/pep-820-pyslot-unified-slot-system-for-the-c-api/105552>\
**Category:** PEPs\
**Tags:** c-api\
**Created:** [January 6, 2026, 1:43pm UTC](https://discuss.python.org/t/pep-820-pyslot-unified-slot-system-for-the-c-api/105552 "2026-01-06T13:43:14Z")\
**Posts on this page:** 1\
**Showing post:** 6

<div class="post-metadata">

**Author:** ![encukou](https://sea2.discourse-cdn.com/flex002/user_avatar/discuss.python.org/encukou/32/2461_2.png) [@encukou](https://discuss.python.org/u/encukou)\
**Post date:** [January 28, 2026, 9:59pm UTC](https://discuss.python.org/t/pep-820-pyslot-unified-slot-system-for-the-c-api/105552/6 "2026-01-28T21:59:00Z")

</div>

I’ve [updated the PEP](https://github.com/python/peps/pull/4788/files) a bit:

- Be clearer that the PEP 793 API added in 3.15 alpha (`PyModExport`, `PyModule_FromSlotsAndSpec`) will be _changed_ to return the new slots.

- Deprecation of things that were documented to not work, but worked in practice:

- Added “third-party slot ID allocation” and “avoiding anonymous unions” to [Rejected Ideas](https://peps.python.org/pep-0820/#rejected-ideas).

---

_[View the full topic](https://discuss.python.org/t/pep-820-pyslot-unified-slot-system-for-the-c-api/105552)._