Message171935
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__). |
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2012-10-04 11:37:14 | max | set | recipients:
+ max, docs@python |
2012-10-04 11:37:14 | max | set | messageid: <1349350634.9.0.571993653286.issue16128@psf.upfronthosting.co.za> |
2012-10-04 11:37:14 | max | link | issue16128 messages |
2012-10-04 11:37:14 | max | create | |
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