Guido rethinking removal of cmp from sort method

[Steven D'Aprano]

On Mon, 14 Mar 2011 12:10:27 +0100, Jean-Michel Pichavant wrote:

> Steven D'Aprano wrote:
>> The removal of cmp from the sort method of lists is probably the most
>> disliked change in Python 3. On the python-dev mailing list at the
>> moment, Guido is considering whether or not it was a mistake.
>>
>> If anyone has any use-cases for sorting with a comparison function that
>> either can't be written using a key function, or that perform really
>> badly when done so, this would be a good time to speak up.
>>
>>
>>
>>
> You seem concerned by this removal, do you have any use-case ?

You seem concerned by my concern. Why do you think I am concerned?

(1) I'm not concerned, but many people are. If you search the archives of 
this newsgroup (mailing list), you'll see that I have defended the 
removal of cmp from sort, e.g. this post:

http://www.mail-archive.com/python-list%40python.org/msg261728.html


(2) If I had a good use-case for keeping cmp, I wouldn't need to ask 
others if they had a good use-case.

As it is, Guido himself has mentioned one such good use for a comparison 
function when sorting. Use of a key function trades off memory for time, 
while sorting with a comparison function makes the opposite trade off, 
using more time for the sake of saving memory. 



-- 
Steven