On Sun, Mar 9, 2008 at 9:02 AM, Armin Rigo <[EMAIL PROTECTED]> wrote: > Hi all, > > In Python 2.5, I made an attempt to make equality consistent for the > various built-in and user-defined method types. I failed, though, as > explained in http://bugs.python.org/issue1617161. The outcome of this > discussion is that, first of all, we need to decide which behavior is > "correct": > > >>> [].append == [].append > True or False? > > (See the issue tracker for why the answer should probably be False.) > > The general question is: if x.foo and y.foo resolve to the same method, > should "x.foo == y.foo" delegate to "x == y" or be based on "x is y"? > > The behavior about this has always been purely accidental, with three > different results for user-defined methods versus built-in methods > versus method wrappers (those who know what the latter are, raise your > hand). > > (Yes, Python < 2.5 managed three different behaviors instead of just > two: one of the types (don't ask me which) would base its equality on > the identity of the 'self', but still compute its hash from the hash of > 'self'...)
They should only compare equal if interchangeable. In the case of a mutable container (ie list), a value comparison of self is irrelevant garbage, so it should always be compared (and hashed) based on identity. IOW, "x = []; x.append == x.append" should be True, and everything else should be False. -- Adam Olsen, aka Rhamphoryncus _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
