René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Change in semantics and much worse performance for enum members.","articleBody":"Given the enum:\r\n```Python\r\nclass Colours(Enum):\r\n    RED = 1\r\n```\r\nIn Python 3.9 and 3.10:\r\n```Python\r\n\u003e\u003e\u003e Colours.__dict__[\"RED\"] is Colours.RED\r\nTrue\r\n\u003e\u003e\u003e Colours.RED.RED\r\n\u003cColours.RED: 1\u003e\r\n\r\n```\r\nIn Python 3.11:\r\n```Python\r\n\u003e\u003e\u003e Colours.__dict__[\"RED\"] is Colours.RED\r\nFalse\r\n\u003e\u003e\u003e Colours.RED.RED\r\nTraceback (most recent call last):\r\n  File \"\u003cstdin\u003e\", line 1, in \u003cmodule\u003e\r\n  File \"/home/mark/repos/cpython/Lib/enum.py\", line 198, in __get__\r\n    raise AttributeError(\r\n    ^^^^^^^^^^^^^^^^^^^^^\r\nAttributeError: \u003cenum 'Colours'\u003e member has no attribute 'RED'\r\n```\r\n\r\nWhile these might seem like minor semantic changes, there is also a large performance impact.\r\nLookup of `Colours.RED` is simple and efficient in 3.10, but involves a lot of indirection and dispatching through the `enum.property` class in 3.11.\r\nThe performance impact is likely to get worse in 3.12, as we optimize more kinds of attributes.\r\n\r\nIntroduced in https://github.com/python/cpython/commit/c314e60388282d9829762fb6c30b12e2807caa19, I believe.\r\n\r\n@pablogsal \r\n@ethanfurman \n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-103236\n* gh-103299\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/markshannon","@type":"Person","name":"markshannon"},"datePublished":"2022-06-16T15:57:50.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":83},"url":"https://github.com/93910/cpython/issues/93910"}