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Documentation about PyTypeObject being part of the Stable ABI #95300
Description
https://docs.python.org/3/c-api/typeobj.html#static-types says:
Also, since PyTypeObject is not part of the stable ABI, any extension modules using static types must be compiled for a specific Python minor version.
https://docs.python.org/3/c-api/type.html#c.PyTypeObject says:
Part of the Stable ABI.
I'm not sure what needs to be fixed, but something does. Can extension modules using the Stable ABI use static types now?
Activity
[-]Documentation about PyTypeObject being part of the stable ABI[/-][+]Documentation about PyTypeObject being part of the Stable ABI[/+]erlend-aasland commentedon Jul 26, 2022
The former quote should probably read Limited API, not Stable ABI. cc. @encukou
kumaraditya303 commentedon Jul 27, 2022
Technically
PyTypeObjectis part of the stable ABI as an opaque struct (whose fields are part of the ABI) because stable ABI uses Limited C API. Maybe it's better to just document it as "part of Limited C API as an opaque struct".encukou commentedon Jul 27, 2022
This is fixed in https://docs.python.org/3.11/c-api/type.html#c.PyTypeObject
But it would make sense to backport to earlier docs.
encukou commentedon Aug 5, 2022
PR is at #95711
ov2k commentedon Aug 5, 2022
I think https://docs.python.org/3/c-api/typeobj.html#static-types still needs to be fixed. https://docs.python.org/3/c-api/stable.html says:
It's not that
PyTypeObjectisn't part of the Stable ABI, but that its members aren't part of the Limited API.encukou commentedon Aug 8, 2022
It's both.
In the limited API/stable ABI,
PyTypeObjectis opaque (and has been since the beginning). The ABI for an opaque struct is just a pointer, so there's nothing specific toPyTypeObjectin the Stable ABI.(The first part of
PyTypeObjecthappens to be stable across releases, but that's because it's needed for declarations without designated initializers using the regular C- API.)erlend-aasland commentedon Aug 8, 2022
Suggesting to close this as fixed.
encukou commentedon Aug 8, 2022
@ov2k, please feel free to comment if you disagree, have other suggestions, or if something is unclear.
(Not sure if you have permission to reopen – if you do, that's also an option.)
ov2k commentedon Aug 11, 2022
That's exactly my point, but perhaps I wasn't being clear enough. https://docs.python.org/3/c-api/typeobj.html#static-types makes no reference to
PyTypeObjectbeing opaque, which is the real reason why extension modules using static types must be compiled for a specific Python minor version. It should say something like:encukou commentedon Aug 17, 2022
It makes sense to me, but I've been thinking about API/ABI way too much :)
Could you send a PR to make this clearer? If not I'll get to it eventually.
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