On Fri, 8 Apr 2016 06:34 pm, Marko Rauhamaa wrote: > Antoon Pardon <antoon.par...@rece.vub.ac.be>: > >> In python2 descending the tree would only involve at most one >> expensive comparison, because using cmp would codify that comparison >> into an integer which would then be cheap to compare with 0. Now in >> python3, I may need to do two expensive comparisons, because there is >> no __cmp__ method, to make such a codefication. > > I think you should base your tree implementation on key.__lt__() only. > Only compare keys using <, nothing else, ever.
I believe that's how list.sort() and sorted() work: py> class Spam(object): ... def __init__(self, n): ... self.n = n ... def __lt__(self, other): ... return self.n < other.n ... def __repr__(self): ... return repr(self.n) ... py> L = [Spam(5), Spam(3), Spam(9), Spam(1), Spam(2)] py> L [5, 3, 9, 1, 2] py> sorted(L) [1, 2, 3, 5, 9] as well as max() and min(). -- Steven -- https://mail.python.org/mailman/listinfo/python-list
