Add guidelines for changing/removing from the Limited API #778
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c-api.rst
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| .. _macro: https://github.com/python/cpython/blob/3.10/Objects/object.c#L2298-L2308 | ||
| .. _redefinition: https://github.com/python/cpython/blob/main/Include/object.h#L603-L606 |
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Is it safe to refer lines in branches instead of tags and commits? For example, Py_NewRef shifted up by 56 lines after it was redefined.
| .. _macro: https://github.com/python/cpython/blob/3.10/Objects/object.c#L2298-L2308 | |
| .. _redefinition: https://github.com/python/cpython/blob/main/Include/object.h#L603-L606 | |
| .. _macro: https://github.com/python/cpython/blob/v3.10.1/Objects/object.c#L2299-L2307 | |
| .. _redefinition: https://github.com/python/cpython/blob/53a03aa/Include/object.h#L547-L550 |
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Thanks for catching that! I failed to copy/paste the right URL.
| - the Backwards Compatibility Policy (:pep:`387`) is followed, and | ||
| - the Stable ABI is not broken -- that is, extensions compiled with | ||
| Limited API of older versions of Python continue to work on | ||
| newer versions of Python. |
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Is it possible to export a function which always fail, if the function has been removed? Removing PyUnicode_InternImmortal() sounds like an interesting challenge: https://bugs.python.org/issue41692
Maybe the function can be replaced with a function... which does nothing but log an error?
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Is it possible to export a function which always fail, if the function has been removed?
I believe, only if the function is not vital for already compiled modules (so its failure won't hamper their main activity). That's actually the whole point of backwards compatibility, to not break third party things that already work.
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IMO, after it's removed from the API and when SSTATE_INTERNED_IMMORTAL needs to be removed, PyUnicode_InternImmortal can do an unpaired INCREF: make the string immortal, but leak it.
See https://www.python.org/dev/peps/pep-0652/#stable-abi:
Future Python versions may deprecate some members of the Stable ABI. Deprecated members will still work, but may suffer from issues like reduced performance or, in the most extreme cases, memory/resource leaks.
c-api.rst
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| its size must not change. | ||
| - Exported symbols (functions and data) must continue to be available | ||
| as exported symbols. Specifically, a function can only be converted | ||
| to a `static inline` function (or macro) if Python also continues to |
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Thanks for the reviews! If you have any more questions, let me know! I thought I left breadcrumbs in all the right places, but I see people coming from directions that are only obvious in retrospect :) |
See the CPython PR: python/cpython#29956
and mailing list discussion: https://mail.python.org/archives/list/[email protected]/thread/64VOMHNR37N4HVPWAHKHJM4UFYJPVKSV/