On Fri, Aug 11, 2017 at 6:56 AM, Marko Rauhamaa <ma...@pacujo.net> wrote: > Chris Angelico <ros...@gmail.com>: > >> On Fri, Aug 11, 2017 at 6:03 AM, Marko Rauhamaa <ma...@pacujo.net> wrote: >>> I see no point in CPython's rotation magic. >> >> Have you ever implemented a hashtable? The most common way to pick a >> bucket for an object is to use modulo on the number of buckets. > > Like I said earlier, CPython takes the __hash__() value and scrambles > it. Look for "perturb" in: > > <URL: https://github.com/python/cpython/blob/master/Objects/dictobject.c> > > From a comment: > > Now the probe sequence depends (eventually) on every bit in the hash > code, and the pseudo-scrambling property of recurring on 5*j+1 is > more valuable, because it quickly magnifies small differences in the > bits that didn't affect the initial index.
I'm aware of this. Doesn't change the fact that the *INITIAL INDEX* is based on exactly what I said. Yaknow? ChrisA -- https://mail.python.org/mailman/listinfo/python-list
