Raymond Hettinger <rhettin...@users.sourceforge.net> added the comment:
[Antoine] > Ok, updated patch: > - uses a 4-bit rotate (not shift) > - avoids comparing an unsigned long to -1 > - tries to streamline the win64 special path (but I can't test) pointer_hash4.patch looks fine to me. Still, I think it's worth considering the simpler and faster: x |= x>>4. The latter doesn't require any special-casing for various pointer sizes. It just works. [Adam] > Adding an arbitrary set of OR, XOR, or add makes me uneasy; > I know enough to do them wrong (reduce entropy), but not > enough to do them right. It's easy enough to prove (just show that the function is reversible) and easy enough to test: assert len(set(ids)) == len(set(map(f, set(ids)))) # for any large group of ids _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue5186> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
