Guido rethinking removal of cmp from sort method

Paul Rubin at nospam.invalid
Fri Apr 1 21:28:16 CEST 2011

Terry Reedy <tjreedy at> writes:
>> Never change an advertised Class interface.
> In Python, class interfaces are no more sacred than module or function
> interfaces. If one takes 'no interface change' literally, then Python
> would have to be frozen. Even bug fixes change a defacto interface.

Oh come on, a interface is advertised if it's documented in the manual,
which cmp is.  There are some undocumented (what you call defacto)
interfaces that you sometimes have to be pragmatically a bit careful
about messing with because people rely on them, but it's almost always
more legitimate to break an undocumented interface than a documented

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