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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Unexpected behavior with dataclasses and weakref","articleBody":"We recently discovered the following error in our project:\r\n`TypeError: descriptor '__weakref__' for 'XYZ' objects doesn't apply to a 'XYZ' object`\r\n\r\nXYZ in our case is a dataclass which uses slots (added v3.10) and weakref_slot (added v3.11) parameters.\r\n\r\nWe further investigated the error and have come to the following example to reproduce it:\r\n\r\n```py\r\nimport dataclasses\r\nimport weakref\r\n\r\n\r\n@dataclasses.dataclass(slots=True, weakref_slot=True)\r\nclass EntityAsDataclass:\r\n    x: int = 10\r\n\r\n\r\nclass Entity:\r\n    __slots__ = (\"x\", \"__weakref__\")\r\n\r\n    def __init__(self, x: int = 10) -\u003e None:\r\n        self.x = x\r\n\r\n\r\ne1 = Entity()\r\ne1_ref = weakref.ref(e1)\r\n\r\ne2 = EntityAsDataclass()\r\ne2_ref = weakref.ref(e2)\r\n\r\n\r\nassert e1.__weakref__ is e1_ref  # works\r\nassert e2.__weakref__ is e2_ref  # fails with \"TypeError: descriptor '__weakref__' for 'EntityAsDataclass' objects doesn't apply to a 'EntityAsDataclass' object\"\r\n```\r\n\r\nI don't know if this is intended, but we expect EntityAsDataclass and Entity to have the same behavior here.\r\n\r\nThanks!\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-102075\n* gh-102662\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/jbaudisch","@type":"Person","name":"jbaudisch"},"datePublished":"2023-02-20T12:23:54.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":1},"url":"https://github.com/102069/cpython/issues/102069"}