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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Fields with single underscore names can mess up dataclasses","articleBody":"A similar issue to https://github.com/python/cpython/issues/96151. ericvsmith mentioned this is worth opening an issue for in https://github.com/python/cpython/pull/98143#issuecomment-1280306360\r\n\r\ndataclasses uses variables with single underscore names as part of its implementation. This can cause interesting errors, for example:\r\n```python\r\nfrom dataclasses import dataclass, field\r\n\r\n@dataclass\r\nclass X:\r\n    x: int = field(default_factory=lambda: 111)\r\n    _dflt_x: int = field(default_factory=lambda: 222)\r\n\r\nX()  # TypeError: '_HAS_DEFAULT_FACTORY_CLASS' object is not callable\r\n```\r\n\r\nThe fix is simple: prefix all of these things with `__dataclass_`, to make name collisions more obviously the user's fault. We already do this for e.g. `__dataclass_self__` in the implementation.\r\n\r\n\u003c!-- gh-linked-prs --\u003e\r\n### Linked PRs\r\n* gh-102032\r\n\u003c!-- /gh-linked-prs --\u003e\r\n","author":{"url":"https://github.com/hauntsaninja","@type":"Person","name":"hauntsaninja"},"datePublished":"2022-10-30T22:48:39.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/98886/cpython/issues/98886"}