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Commit6e1b31b

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miss-islingtonJelleZijlstrancoghlan
authored
[3.14]gh-135228: When@DataClass(slots=True) replaces a dataclass, make the original class collectible (GH-136893) (#136960)
gh-135228: When@DataClass(slots=True) replaces a dataclass, make the original class collectible (GH-136893)An interesting hack, but more localized in scope thanGH-135230.This may be a breaking change if people intentionally keep the original class aroundwhen using `@dataclass(slots=True)`, and then use `__dict__` or `__weakref__` on theoriginal class.(cherry picked from commit46cbdf9)Co-authored-by: Jelle Zijlstra <jelle.zijlstra@gmail.com>Co-authored-by: Alyssa Coghlan <ncoghlan@gmail.com>
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‎Lib/dataclasses.py‎

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@@ -1338,6 +1338,13 @@ def _add_slots(cls, is_frozen, weakref_slot, defined_fields):
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or_update_func_cell_for__class__(member.fdel,cls,newcls)):
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break
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# gh-135228: Make sure the original class can be garbage collected.
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# Bypass mapping proxy to allow __dict__ to be removed
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old_cls_dict=cls.__dict__|_deproxier
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old_cls_dict.pop('__dict__',None)
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if"__weakref__"incls.__dict__:
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delcls.__weakref__
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returnnewcls
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@@ -1732,3 +1739,11 @@ def _replace(self, /, **changes):
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# changes that aren't fields, this will correctly raise a
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# TypeError.
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returnself.__class__(**changes)
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# Hack to the get the underlying dict out of a mappingproxy
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# Use it with: cls.__dict__ | _deproxier
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class_Deproxier:
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def__ror__(self,other):
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returnother
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_deproxier=_Deproxier()

‎Lib/test/test_dataclasses/__init__.py‎

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@@ -3804,6 +3804,41 @@ class WithCorrectSuper(CorrectSuper):
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# that we create internally.
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self.assertEqual(CorrectSuper.args, ["default","default"])
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deftest_original_class_is_gced(self):
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# gh-135228: Make sure when we replace the class with slots=True, the original class
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# gets garbage collected.
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defmake_simple():
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@dataclass(slots=True)
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classSlotsTest:
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pass
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returnSlotsTest
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defmake_with_annotations():
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@dataclass(slots=True)
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classSlotsTest:
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x:int
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returnSlotsTest
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defmake_with_annotations_and_method():
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@dataclass(slots=True)
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classSlotsTest:
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x:int
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defmethod(self)->int:
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returnself.x
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returnSlotsTest
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formakein (make_simple,make_with_annotations,make_with_annotations_and_method):
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withself.subTest(make=make):
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C=make()
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support.gc_collect()
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candidates= [clsforclsinobject.__subclasses__()ifcls.__name__=='SlotsTest'
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andcls.__firstlineno__==make.__code__.co_firstlineno+1]
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self.assertEqual(candidates, [C])
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classTestDescriptors(unittest.TestCase):
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deftest_set_name(self):
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When:mod:`dataclasses` replaces a class with a slotted dataclass, the
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original class is now garbage collected again. Earlier changes in Python
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3.14 caused this class to remain in existence together with the replacement
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class synthesized by:mod:`dataclasses`.

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