Issue 16128: hashable documentation error (original) (raw)

Issue16128

Created on 2012-10-04 11:37 by max, last changed 2022-04-11 14:57 by admin. This issue is now closed.

Messages (4)
msg171935 - (view)	Author: Max (max) *	Date: 2012-10-04 11:37
http://docs.python.org/dev/glossary.html?highlight=hashable says: Objects which are instances of user-defined classes are hashable by default; they all compare unequal, and their hash value is their id(). Since x == x returns True by default, so "they all compare unequal" isn't quite right. In addition, both the above paragraph and http://docs.python.org/dev/reference/datamodel.html?highlight=__eq__#object.__hash__ say: User-defined classes have __eq__() and __hash__() methods by default; with them, all objects compare unequal (except with themselves) and x.__hash__() returns an appropriate value such that x == y implies both that x is y and hash(x) == hash(y). This is correct, but may leave some confusion with the reader about what happens to a subclass of a built-in class (which doesn't use the default behavior, but instead simply inherits the parent's __hash__ and __eq__).
msg172113 - (view)	Author: Andrew Svetlov (asvetlov) *	Date: 2012-10-05 18:57
Please write what exact text you want to see in documentation.
msg181060 - (view)	Author: Roundup Robot (python-dev)	Date: 2013-02-01 03:20
New changeset 79a021beaf58 by Ezio Melotti in branch '2.7': #16128: clarify that instances of user-defined classes compare equal with themselves. http://hg.python.org/cpython/rev/79a021beaf58 New changeset e84c5cf92b6f by Ezio Melotti in branch '3.2': #16128: clarify that instances of user-defined classes compare equal with themselves. http://hg.python.org/cpython/rev/e84c5cf92b6f New changeset d9255c100971 by Ezio Melotti in branch '3.3': #16128: merge with 3.2. http://hg.python.org/cpython/rev/d9255c100971 New changeset 1890c63f6153 by Ezio Melotti in branch 'default': #16128: merge with 3.3. http://hg.python.org/cpython/rev/1890c63f6153
msg181062 - (view)	Author: Ezio Melotti (ezio.melotti) *	Date: 2013-02-01 03:22
I addressed the first comment. The paragraph in datamodel.html looks ok to me, so I left it unchanged. Feel free to reopen the issue if you have a specific suggestion that could improve that section.