Jeff Shannon <[EMAIL PROTECTED]> wrote: ... > hashes) is that, for a well-behaved hash function, then A == B should > imply that hash(A) == hash(B). (The reverse is *not* true, however -- > hash(A) == hash(B) does not necessarily say anything about whether A == B.) > > If that is a correct condition for a well-behaved hash function, then it
Yep, I consider it part of the axioms of hash. > is indeed impossible to have a well-behaved hash function that can be > useful in the face of object mutation. For something like a list, one > can only define a poorly-behaved hash-like function. In terms of performance, yes. In terms of satisfying the axioms, no; just "def __hash__(self): return 23" (or any other int) and the axioms will be satisfied. (Every isntance will hash to the same bucket, so, performance sucks -- but, formally, everything IS fine;-). Alex -- http://mail.python.org/mailman/listinfo/python-list
