[Python-Dev] Should the default equality operator compare values instead of identities?

Noam Raphael noamraph at gmail.com
Wed Nov 2 22:11:25 CET 2005

I've looked for classes in my /usr/lib/python2.4 directory. I won't go
over all the 7346 classes that were found there, but let's see:

"identity objects" that will continue to work because they contain
other "identity objects"
SocketServer, and everything which inherits from it (like HTTPServer)
csv (contains _csv objects)

"value objects" that would probably gain a meaningful equality operator
markupbase, HTMLParser
HexBin, BinHex
AST Nodes

Cookie - inherits from dict its __eq__ method.

I'll stop here. I was not strictly scientific, because I chose classes
that I thought that I might guess what they do easily, and perhaps
discarded classes that didn't look interesting to me. But I didn't
have any bad intention when choosing the classes. I have seen no class
that the change would damage its equality operator. I have seen quite
a lot of classes which didn't define an equality operator, and that a
value-based comparison would be the right way to compare them.

I'm getting more convinced in my opinion.


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