Guido rethinking removal of cmp from sort method

Terry Reedy tjreedy at
Fri Apr 1 22:21:33 EDT 2011

On 4/1/2011 3:22 PM, Paul Rubin wrote:

>> 2to3 could probably gain a fixer to change
>> .sort(cmp=f) # to
>> import functools import cmp_to_key
>> .sort(key=functools.cmp_to_key(f))
>> I know some would not like this because interface change is not their
>> real concern.
> Looks like a good idea.  There is an efficiency hit from the above in
> some situations, but at least it prevents code from breaking, so unless
> there's some drawback I'm not currently spotting, it's better than
> nothing and I'd endorse adding such a wrapper.  2to3 should show some
> kind of diagnostic and maybe put a comment into the output code,
> when it does that particular transformation, since most of the
> time there's probably a better way to write the key function.

rewriting cmp_to_key in C is underway

Terry Jan Reedy

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