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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"inspect.getsource() on sourceless dataclass raises undocumented exception","articleBody":"\u003c!--\r\n  If you're new to Python and you're not sure whether what you're experiencing is a bug, the CPython issue tracker is not\r\n  the right place to seek help. Consider the following options instead:\r\n\r\n  - reading the Python tutorial: https://docs.python.org/3/tutorial/\r\n  - posting in the \"Users\" category on discuss.python.org: https://discuss.python.org/c/users/7\r\n  - emailing the Python-list mailing list: https://mail.python.org/mailman/listinfo/python-list\r\n  - searching our issue tracker (https://github.com/python/cpython/issues) to see if\r\n    your problem has already been reported\r\n--\u003e\r\n\r\n# Bug report\r\n\r\nIf I run the following program in Python 3.10:\r\n\r\n```py\r\nfrom dataclasses import dataclass\r\nfrom inspect import getsource\r\n\r\ndefs = {}\r\nexec(\r\n    \"\"\"\r\n@dataclass\r\nclass C:\r\n    \"The source for this class cannot be located.\"\r\n\"\"\",\r\n    {\"dataclass\": dataclass},\r\n    defs,\r\n)\r\n\r\ntry:\r\n    getsource(defs[\"C\"])\r\nexcept OSError:\r\n    print(\"Got the documented exception.\")\r\n```\r\n\r\nThe output is:\r\n\r\n```\r\n$ python sourceless_dataclass.py \r\nTraceback (most recent call last):\r\n  File \"\u003cpath\u003e/sourceless_dataclass.py\", line 16, in \u003cmodule\u003e\r\n    getsource(defs[\"C\"])\r\n  File \"/usr/lib/python3.10/inspect.py\", line 1147, in getsource\r\n    lines, lnum = getsourcelines(object)\r\n  File \"/usr/lib/python3.10/inspect.py\", line 1129, in getsourcelines\r\n    lines, lnum = findsource(object)\r\n  File \"/usr/lib/python3.10/inspect.py\", line 940, in findsource\r\n    file = getsourcefile(object)\r\n  File \"/usr/lib/python3.10/inspect.py\", line 817, in getsourcefile\r\n    filename = getfile(object)\r\n  File \"/usr/lib/python3.10/inspect.py\", line 786, in getfile\r\n    raise TypeError('{!r} is a built-in class'.format(object))\r\nTypeError: \u003cclass 'C'\u003e is a built-in class\r\n```\r\n\r\nThe [documentation](https://docs.python.org/3.10/library/inspect.html#inspect.getsource) states that `OSError` can be raised but does not mention `TypeError`.\r\n\r\nThe implementation of `inspect.getsource()` assumes that if a class has no `__module__` attribute, it must be a built-in class, but a sourceless dataclass doesn't have a `__module__` attribute either. I don't know whether this is a bug in `getsource()` or whether the generation of the dataclass should set `__module__` to `'__main__'`, but in any case the behavior is not as documented.\r\n\r\n# Your environment\r\n\r\n- CPython versions tested on: Python 3.10.6\r\n- Operating system and architecture: Ubuntu Linux 18.04\r\n\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-101689\n* gh-102969\n* gh-102970\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/mthuurne","@type":"Person","name":"mthuurne"},"datePublished":"2022-10-13T11:53:35.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":8},"url":"https://github.com/98239/cpython/issues/98239"}