Maric Michaud wrote:
Le Thursday 04 September 2008 22:26:53 Ruediger, vous avez écrit :
class foo(list): __hash__ = lambda x: id(x)Wow ! You are really going on trouble with this, believe me there is a real good reason for list not to be hashable. A dictionnary or set containing some of your foo is virtually inconsistent, read carefully the manual about prerequesites for dict keys, they *need* to be immutable.
Well, that's not entirely true. They need to be not mutated while they are in the dictionary, certainly. At least not in ways that affect equality testing. In this case, one would also have to override list.__eq__ to also compare by identity, too. Then you could mutate the lists to your heart's content and the dictionary wouldn't care.
-- Robert Kern "I have come to believe that the whole world is an enigma, a harmless enigma that is made terrible by our own mad attempt to interpret it as though it had an underlying truth." -- Umberto Eco -- http://mail.python.org/mailman/listinfo/python-list
