On Mon, 4 Dec 2017 08:45:55 +0200 Serhiy Storchaka <storch...@gmail.com> wrote: > 04.12.17 01:06, Chris Barker пише: > > So: has this already been brought up and rejected? > > https://bugs.python.org/issue20632 > > > Am I imagining the performance benefits? > > This will add an additional overhead. This will be even slower than > passing the key function, since you will need to look up the __key__ > method in every item.
That is a reasonable objection. However, looking up a tp_XXX slot is very cheap. > Yes, it is too special-case. I don't see any advantages in comparison > with defining the __lt__ method. There are definitely advantages. Sorting calls __lt__ for each comparison (that is, O(n log n) times) while __key__ would only be called once per item at the start (that is, O(n) times). > It will be rather confusing if > different methods of sorting produce inconsistent order. If __key__ is inconsistent with __lt__, it is the same error as making __lt__ inconsistent with __gt__. And there could be a decorator that generates all comparison methods from __key__. Regards Antoine. _______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/
