[issue29089] Python 2 dictionary keys described incorrectly
New submission from Xezlec: In section 5.5 on the page https://docs.python.org/2/tutorial/datastructures.html#dictionaries the requirements given for dictionary keys are not correct. Specifically, it is claimed that only immutable objects (and tuples containing only immutable objects) may be used as keys. This is false, as user-defined mutable objects may be used as keys. I suggest rewording along these lines: "Only user-defined objects and immutable built-in types may be used as keys. Although allowed, it is bad practice to use a mutable user-defined object as a key when equality is determined in any way other than identity (the default)." -- assignee: docs@python components: Documentation messages: 284135 nosy: Xezlec, docs@python priority: normal severity: normal status: open title: Python 2 dictionary keys described incorrectly versions: Python 2.7 ___ Python tracker <http://bugs.python.org/issue29089> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue29089] dictionary keys described incorrectly in tutorial
Xezlec added the comment: > It's the tutorial. Probably better to just leave it alone. Precise > understanding can come later. But the problem isn't that it's imprecise. It's flat-out wrong. My opinion would be that it's always a bad idea to put wrong information in the documentation, especially when it's the first Google hit. It can lead to all sorts of confusion and frustration (as it did for me). Users are likely to assume documentation from any official source is the final word. If precision is the problem, could it be reworded to be more vague? -- ___ Python tracker <http://bugs.python.org/issue29089> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue29089] dictionary keys described incorrectly in tutorial
Xezlec added the comment: > Perhaps the sentence about a tuple pointing to a mutable could be tightened > up, though, by saying that if a tuple points to something that can not itself > be a dictionary key, then that tuple can not be a dictionary key. That would be great. Thank you. > I feel assuming early part of tutorial as final word bad practice. Alright. If that's how both of you feel, then it can't be helped. But if that's how it is, then maybe it would be a good idea to make the tutorial more distinct? Right now, the only way I can tell Google has landed me on a tutorial page as opposed to a reference page is the word "tutorial" in the URL and in small print at the very top of the page. They're styled similarly. I never even realized they were separate things until today (let alone that one of them must be read skeptically). Sorry to take up your time. Thanks for listening. -- ___ Python tracker <http://bugs.python.org/issue29089> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
