bpo-44524: Do not set _name of _SpecialForm without need#27861
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Becase setting non-empty _name affects other behavior. In most cases __name__ can be derived from __origin__.__name__.
gvanrossum commented Aug 20, 2021
What does Ken Jin say? |
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LGTM. Personally I don't think setting _name on _SpecialForms will break anything (because they aren't subclassable, and any methods they need are overridden, so their MRO doesn't matter). But I've been wrong on multiple occasions at this point 😉 , so let's just be safe. From a technical standpoint, Serhiy's solution is much cleaner (and faster) too.
PS @serhiy-storchaka , you can do the same for Annotated and copy the test over from my PR #27841. I'm closing that so we don't have to deal with merging multiple PRs.
| def__getattr__(self, attr): | ||
| ifattrin{'__name__', '__qualname__'}: | ||
| returnself._name | ||
| returnself._nameorself.__origin__.__name__ |
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This solution is so nice. I wish I'd thought about this a little deeper when I proposed the original one:(.
Anyways if I'm not wrong, __origin__ will always be set on all GenericAlias to some type, so this should always succeed.
| return_UnionGenericAlias(self, parameters, name="Optional") | ||
| return_UnionGenericAlias(self, parameters) |
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Will there be a subtle difference between how the two behaves since one sets name and the other doesn't?
I would think not but I'm not sure.
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Setting _name affects subclassing and pickling/copying. Union[] and Optional[] are not subclassable, and special implementation of __reduce__ was added in previous commits. If there are other difference, I do not know.
miss-islington commented Aug 21, 2021
Thanks @serhiy-storchaka for the PR 🌮🎉.. I'm working now to backport this PR to: 3.10. |
bedevere-bot commented Aug 21, 2021
GH-27871 is a backport of this pull request to the 3.10 branch. |
) Because setting non-empty _name affects behavior of other code. In most cases __name__ can be derived from __origin__.__name__. (cherry picked from commit 4ceec49) Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
serhiy-storchaka commented Aug 21, 2021
It is easier to merge them separately. There are no conflicts. |
6 participants
Because setting non-empty
_nameaffects other behavior.In most cases
__name__can be derived from__origin__.__name__.https://bugs.python.org/issue44524