Mark Dickinson <dicki...@gmail.com> added the comment: Hmm. This doesn't look like something that's easy to fix without affecting existing correct code; given that the behaviour has been around for a while (I'm not sure exactly how long), and that the issue is gone in 3.x, I suspect it may not be worth trying.
Analysis: for classic classes, the ceval loop calls PySequence_GetSlice, which corrects the negative indices by adding the length of the sequence (as described in the docs) and then calls the tp_as_sequence->sq_slice slot on the type. That ends up calling instance_slice (in Objects/classobject.c), which discovers that the class doesn't implement __getslice__ and so passes the adjusted slice on to the __getitem__ method. I'm not sure how this could be changed to get the correct behaviour: PySequence_GetSlice would somehow need to know that it was going to end up calling __getitem__ rather than __getslice__. Raymond, any thoughts? ---------- nosy: +mark.dickinson, rhettinger _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue7532> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
