Antoon Pardon <antoon.par...@rece.vub.ac.be> writes: > You don't seem to understand. I only do two comparisons and no the > equality is not necesarrily cheaper. > > I am talking about the difference between the following two: > > if arg.key < node.key: # possible expensive computation > go_left() > elif arg.key == node.key # possible expensive computation > found_node() > else: > go_right() > > and > > delta = cmp(arg.key, node.key) # possible expensive computation > if delta < 0: # cheap computation > go_left() > elif delta == 0: # cheap computation > found_node() > else: > go_right()
I find that a dubious claim. The ‘cmp’ implementation must decide *at least* between three conditions: less-than, equal-to, greater-than. That is *at least* two inflection points. The implementation of ‘__lt__’ and the implementation of ‘__eq__’ each only need to decide two conditions (true, false). So that is *at most* two inflection points. If you're saying the latter implementation is somehow *more* expensive than the former, I think the implementations are suspect and likely can be improved: at least parity should be possible, to the point of statistical insignificance. -- \ “Perchance you who pronounce my sentence are in greater fear | `\ than I who receive it.” —Giordano Bruno, burned at the stake by | _o__) the Catholic church for the heresy of heliocentrism, 1600-02-16 | Ben Finney -- https://mail.python.org/mailman/listinfo/python-list
