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Remove _ProxyFile.__class_getitem__ #140808
Description
Feature or enhancement
Proposal:
#19425 made the internal file wrapper mailbox._ProxyFile generic, probably because it was generic over AnyStr in typeshed. (Unchanged since mailbox.pyi was added in python/typeshed#3427. There was no discussion about it back then.)
_ProxyFile does not need to be generic, as it's only used internally by mailbox.py and is always initialized with a binary file object (as returned by open()). In fact, this now complicates the stubs for mailbox.pyi, because we need to carry the generic-ness of this class through to other protocols. See python/typeshed#14950 for details.
I suggest to remove __class_getitem__ again, although this probably needs to go through the deprecation process, even though this is an internal class?
Cc @emmatyping @JelleZijlstra @AlexWaygood
Has this already been discussed elsewhere?
This is a minor feature, which does not need previous discussion elsewhere
Links to previous discussion of this feature:
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emmatyping commentedon Oct 31, 2025
I think this makes sense to remove. As you say, these are private APIs, so per PEP 387:
Looking on GitHub, I saw 2 references to the classes at all, neither in typed contexts, so I think it should be safe to remove
__class_getitem__, especially since these are internal details users shouldn't be interacting with.gh-140808: Remove __class_getitem__ from mailbox._ProxyFile (#140838)
pythongh-140808: Remove __class_getitem__ from mailbox._ProxyFile (py…