[Python-Dev] PEP 3144 review. (original) (raw)

Dj Gilcrease digitalxero at gmail.com
Mon Sep 28 17:30:05 CEST 2009

On Mon, Sep 28, 2009 at 8:56 AM, Guido van Rossum <guido at python.org> wrote:

Hold it right there! That's wrong. You can't have two objects that compare equal but whose hashes differ. It will break dict lookup. The other way around is fine: two objects may differ and still have the same hash.

mm I never knew that, guess I'll go fix my patch to change the hash method as well, though when I tested it dict lookup seemed to work fine

net1 = IPNetwork("10.1.2.0/29") i = 0 test = {} for ip in net1: test[IPNetwork("%s/29" %(ip))] = i i += 1

print test[IPv4Network('10.1.2.4/29')] 4 print test {IPv4Network('10.1.2.0/29'): 0, IPv4Network('10.1.2.1/29'): 1, IPv4Network('10.1.2.2/29'): 2, IPv4Network('10.1.2.3/29'): 3, IPv4Network('10.1.2.4/29'): 4, IPv4Network('10.1.2.5/29'): 5, IPv4Network('10.1.2.6/29'): 6, IPv4Network('10.1.2.7/29'): 7}

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