[Python-3000] Total ordering and cmp (original) (raw)

Guido van Rossum guido at python.org
Wed Mar 21 22:36:05 CET 2007

On 3/21/07, Georg Brandl <g.brandl at gmx.net> wrote:

Terry Reedy schrieb: > "Georg Brandl" <g.brandl at gmx.net> wrote in message > news:etrj1a$l9a$1 at sea.gmane.org... > | Yes, but dictionaries had an explicit ordering in dictcompare() which > was > | deleted. > > Is dictcompare something added in 2.5? It is neither a builtin or dict > method in 2.4.

No, it is a C function in dictobject.c, in Python available as dict.cmp. > In any case, this point is that dict ordering is as arbitrary as ordering, > for instance, a dict and a string. Since Guido stopped the experiment of > totally ordering all objects when complex nums were added, consistency > suggests that all fake orderings be eliminated, leaving only the order of > numbers, characters, and sequences of comparable objects. It was not really that arbitrary. There was a defined algorithm, and it made some sense (at least for 1-item-dicts).

It was well-defined because I had to do something that depended only on the keys and values and not on object identities etc. I never considered it userful and I don't know of anyone who used it.

-- --Guido van Rossum (home page: http://www.python.org/~guido/)

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