Re: Guido rethinking removal of cmp from sort method

From	Paul Rubin <no.email@nospam.invalid>
Newsgroups	comp.lang.python
Subject	Re: Guido rethinking removal of cmp from sort method
References	(3 earlier) <4d94326c$0$30003$c3e8da3$5496439d@news.astraweb.com> <R1elp.6224$sP1.5155@newsfe07.iad> <mailman.67.1301639410.2990.python-list@python.org> <7x8vvue7or.fsf@ruckus.brouhaha.com> <mailman.91.1301684281.2990.python-list@python.org>
Date	2011-04-01 12:22 -0700
Message-ID	<7xfwq1srn0.fsf@ruckus.brouhaha.com> (permalink)
Organization	Nightsong/Fort GNOX

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Terry Reedy <tjreedy@udel.edu> writes:
>> What happens then is you define a new interface.
> Like key= versus cmp=

Well, in an untyped language like Python, adding a feature to an
interface doesn't require defining a new interface unless you change
something incompatibly.  key= is very useful but it can be added without
breaking cmp= .

> 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.

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Re: Guido rethinking removal of cmp from sort method harrismh777 <harrismh777@charter.net> - 2011-03-31 01:34 -0500
  Re: Guido rethinking removal of cmp from sort method Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-03-31 07:51 +0000
    Re: Guido rethinking removal of cmp from sort method harrismh777 <harrismh777@charter.net> - 2011-04-01 01:13 -0500
      Re: Guido rethinking removal of cmp from sort method Chris Angelico <rosuav@gmail.com> - 2011-04-01 17:30 +1100
        Re: Guido rethinking removal of cmp from sort method Paul Rubin <no.email@nospam.invalid> - 2011-04-01 00:45 -0700
          Re: Guido rethinking removal of cmp from sort method Terry Reedy <tjreedy@udel.edu> - 2011-04-01 12:59 -0400
          Re: Guido rethinking removal of cmp from sort method Terry Reedy <tjreedy@udel.edu> - 2011-04-01 14:57 -0400
            Re: Guido rethinking removal of cmp from sort method Paul Rubin <no.email@nospam.invalid> - 2011-04-01 12:22 -0700
              Re: Guido rethinking removal of cmp from sort method Terry Reedy <tjreedy@udel.edu> - 2011-04-01 22:21 -0400
              Re: Guido rethinking removal of cmp from sort method Antoon Pardon <Antoon.Pardon@rece.vub.ac.be> - 2011-04-04 11:34 +0200
                Re: Guido rethinking removal of cmp from sort method Lie Ryan <lie.1296@gmail.com> - 2011-04-04 23:35 +1000
                Re: Guido rethinking removal of cmp from sort method Terry Reedy <tjreedy@udel.edu> - 2011-04-04 13:26 -0400
                Re: Guido rethinking removal of cmp from sort method Terry Reedy <tjreedy@udel.edu> - 2011-04-04 15:05 -0400
              Re: Guido rethinking removal of cmp from sort method Terry Reedy <tjreedy@udel.edu> - 2011-04-04 13:22 -0400
          Re: Guido rethinking removal of cmp from sort method Terry Reedy <tjreedy@udel.edu> - 2011-04-01 15:37 -0400
            Re: Guido rethinking removal of cmp from sort method Paul Rubin <no.email@nospam.invalid> - 2011-04-01 14:37 -0700
              Re: Guido rethinking removal of cmp from sort method Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-04-02 00:42 +0000
                Re: Guido rethinking removal of cmp from sort method Paul Rubin <no.email@nospam.invalid> - 2011-04-01 19:31 -0700
              Re: Guido rethinking removal of cmp from sort method Benjamin Peterson <benjamin@python.org> - 2011-04-02 03:31 +0000
                Re: Guido rethinking removal of cmp from sort method Paul Rubin <no.email@nospam.invalid> - 2011-04-01 20:43 -0700
            Re: Guido rethinking removal of cmp from sort method Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-04-02 10:13 +0000
              Re: Guido rethinking removal of cmp from sort method rantingrick <rantingrick@gmail.com> - 2011-04-04 14:10 -0700
                Re: Guido rethinking removal of cmp from sort method Chris Angelico <rosuav@gmail.com> - 2011-04-05 07:41 +1000
                Re: Guido rethinking removal of cmp from sort method rantingrick <rantingrick@gmail.com> - 2011-04-04 15:16 -0700
                Re: Guido rethinking removal of cmp from sort method Chris Angelico <rosuav@gmail.com> - 2011-04-05 08:36 +1000
                Re: Guido rethinking removal of cmp from sort method Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-04-05 00:47 +0000
                Re: Guido rethinking removal of cmp from sort method harrismh777 <harrismh777@charter.net> - 2011-04-04 17:09 -0500
                Re: Guido rethinking removal of cmp from sort method Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-04-04 23:25 +0000
                Re: Guido rethinking removal of cmp from sort method harrismh777 <harrismh777@charter.net> - 2011-04-04 20:16 -0500
                Re: Guido rethinking removal of cmp from sort method Terry Reedy <tjreedy@udel.edu> - 2011-04-05 00:54 -0400
      Re: Guido rethinking removal of cmp from sort method Terry Reedy <tjreedy@udel.edu> - 2011-04-01 13:06 -0400
        Re: Guido rethinking removal of cmp from sort method Paul Rubin <no.email@nospam.invalid> - 2011-04-01 12:28 -0700
        Re: Guido rethinking removal of cmp from sort method harrismh777 <harrismh777@charter.net> - 2011-04-01 23:54 -0500
          Re: Guido rethinking removal of cmp from sort method Chris Angelico <rosuav@gmail.com> - 2011-04-02 16:06 +1100
            Re: Guido rethinking removal of cmp from sort method harrismh777 <harrismh777@charter.net> - 2011-04-02 00:17 -0500
              Re: Guido rethinking removal of cmp from sort method Chris Angelico <rosuav@gmail.com> - 2011-04-02 17:17 +1100
                Re: Guido rethinking removal of cmp from sort method harrismh777 <harrismh777@charter.net> - 2011-04-02 03:29 -0500
                Re: Guido rethinking removal of cmp from sort method Brian Quinlan <brian@sweetapp.com> - 2011-04-02 22:14 +1100
                Re: Guido rethinking removal of cmp from sort method harrismh777 <harrismh777@charter.net> - 2011-04-03 00:30 -0500
                Re: Guido rethinking removal of cmp from sort method geremy condra <debatem1@gmail.com> - 2011-04-02 22:46 -0700
                Re: Guido rethinking removal of cmp from sort method harrismh777 <harrismh777@charter.net> - 2011-04-03 02:17 -0500
                Re: Guido rethinking removal of cmp from sort method Brian Quinlan <brian@sweetapp.com> - 2011-04-03 16:36 +1000
                Re: Guido rethinking removal of cmp from sort method Terry Reedy <tjreedy@udel.edu> - 2011-04-02 22:14 -0400
                Re: Guido rethinking removal of cmp from sort method harrismh777 <harrismh777@charter.net> - 2011-04-03 00:26 -0500
                Re: Guido rethinking removal of cmp from sort method Terry Reedy <tjreedy@udel.edu> - 2011-04-04 01:38 -0400
          Re: Guido rethinking removal of cmp from sort method Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-04-02 09:39 +0000
            Re: Guido rethinking removal of cmp from sort method harrismh777 <harrismh777@charter.net> - 2011-04-03 00:09 -0500
  Re: Guido rethinking removal of cmp from sort method Terry Reedy <tjreedy@udel.edu> - 2011-03-31 11:26 -0400
    Re: Guido rethinking removal of cmp from sort method harrismh777 <harrismh777@charter.net> - 2011-04-01 01:44 -0500
      Re: Guido rethinking removal of cmp from sort method Terry Reedy <tjreedy@udel.edu> - 2011-04-01 15:13 -0400
        Re: Guido rethinking removal of cmp from sort method John Bokma <john@castleamber.com> - 2011-04-01 13:42 -0600
          Re: Guido rethinking removal of cmp from sort method Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-04-02 00:58 +0000
        Re: Guido rethinking removal of cmp from sort method harrismh777 <harrismh777@charter.net> - 2011-04-02 00:07 -0500

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