Re: code review

Date	2012-07-01 00:05 +0200
From	Thomas Jollans <t@jollybox.de>
Subject	Re: code review
References	(8 earlier) <VlJHr.500117$jl.112442@fx19.am4> <mailman.1659.1341089444.4697.python-list@python.org> <87wr2oecf6.fsf@dpt-info.u-strasbg.fr> <4FEF7117.7000109@jollybox.de> <jsns6l$7c0$1@dough.gmane.org>
Newsgroups	comp.lang.python
Message-ID	<mailman.1663.1341093928.4697.python-list@python.org> (permalink)

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On 06/30/2012 11:47 PM, Terry Reedy wrote:
> On 6/30/2012 5:35 PM, Thomas Jollans wrote:
>> On 06/30/2012 11:07 PM, Alain Ketterlin wrote:
>>> Thomas Jollans <t@jollybox.de> writes:
>>>
>>>>>>>> def is_valid_password(password):
>>>>>>>>      return mud.minpass <= len(password) <= mud.maxpass
>>>
>>>> Which of the two comparisons is done first anyway?
>>>> "In the face of ambiguity, refuse the temptation to guess."
>>>
>>> There is no ambiguity. See the language reference:
>>
>> Of course it's technically clearly defined, but the syntax isn't
>> explicit. To know what the order is (or whether there is an order!) one
>> has to consult the language reference (which shouldn't be necessary), or
>> make an educated guess, which would almost certainly be correct, but
>> we're supposed to refuse the temptation to guess, right?
> 
> Python pretty consistently evaluates expressions and equal precedence
> operators left to right. 

Yes. My sole point, really, is that "normally", one would expect these
two expressions to be equivalent:

a < b < c
(a < b) < c

This is clearly not true. That's the inconsistency here with the rest of
the language. As soon as you read it as a ternary operator, the two
comparisons are logically simultaneous. Doing the left hand comparison
first is clearly the intuitive thing to do, but it's still, strictly
speaking, arbitrary. Intuitive, clearly defined, but arbitrary.

The ternary conditional operator is a different beast because its
sub-operators "if" and "else" aren't also binary operators, so it's
obvious that it's parsed differently.

> One really should learn that. No
> 'implementation defined' ambiguity.

Thread

code review "Littlefield, Tyler" <tyler@tysdomain.com> - 2012-06-28 20:57 -0600
  Re: code review alex23 <wuwei23@gmail.com> - 2012-06-28 20:58 -0700
    Re: code review Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-06-29 07:31 +0000
      Re: code review Chris Angelico <rosuav@gmail.com> - 2012-06-29 17:42 +1000
      Re: code review "Littlefield, Tyler" <tyler@tysdomain.com> - 2012-06-29 09:03 -0600
        Re: code review Alister <alister.ware@ntlworld.com> - 2012-06-29 19:41 +0000
          Re: code review MRAB <python@mrabarnett.plus.com> - 2012-06-29 21:09 +0100
          Re: code review "Martin P. Hellwig" <martin.hellwig@gmail.com> - 2012-06-29 13:27 -0700
            Re: code review Alister <alister.ware@ntlworld.com> - 2012-06-29 20:43 +0000
              Re: code review Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2012-06-29 19:02 -0400
              Re: code review Terry Reedy <tjreedy@udel.edu> - 2012-06-29 23:02 -0400
          Re: code review "Littlefield, Tyler" <tyler@tysdomain.com> - 2012-06-29 14:49 -0600
            Re: code review Alister <alister.ware@ntlworld.com> - 2012-06-30 09:31 +0000
              Re: code review Alister <alister.ware@ntlworld.com> - 2012-06-30 09:36 +0000
          Re: code review Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-06-30 02:28 +0000
            Re: code review Alister <alister.ware@ntlworld.com> - 2012-06-30 09:22 +0000
          Re: code review Terry Reedy <tjreedy@udel.edu> - 2012-06-29 23:00 -0400
        Re: code review Alister <alister.ware@ntlworld.com> - 2012-06-30 10:04 +0000
          Re: code review Peter Otten <__peter__@web.de> - 2012-06-30 12:29 +0200
            Re: code review Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-06-30 20:39 +0200
              Re: code review Thomas Jollans <t@jollybox.de> - 2012-06-30 21:38 +0200
                Re: code review Alister <alister.ware@ntlworld.com> - 2012-06-30 20:30 +0000
                Re: code review Thomas Jollans <t@jollybox.de> - 2012-06-30 22:50 +0200
                Re: code review Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2012-06-30 23:07 +0200
                Re: code review Thomas Jollans <t@jollybox.de> - 2012-06-30 23:35 +0200
                Re: code review Terry Reedy <tjreedy@udel.edu> - 2012-06-30 17:47 -0400
                Re: code review Thomas Jollans <t@jollybox.de> - 2012-07-01 00:05 +0200
                Re: code review Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2012-07-01 01:03 +0200
                Re: code review Ben Finney <ben+python@benfinney.id.au> - 2012-07-01 10:08 +1000
                Re: code review Chris Angelico <rosuav@gmail.com> - 2012-07-01 10:37 +1000
                Re: code review Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-01 03:23 +0000
                Re: code review Chris Angelico <rosuav@gmail.com> - 2012-07-01 13:48 +1000
                Re: code review Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-01 06:54 +0000
                Re: code review Chris Angelico <rosuav@gmail.com> - 2012-07-01 16:59 +1000
                Re: code review Terry Reedy <tjreedy@udel.edu> - 2012-07-01 05:55 -0400
                Re: code review Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-02 01:26 +0000
                Re: code review Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-07-13 12:30 +0000
                Re: code review Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-13 15:04 +0000
                Re: code review Chris Angelico <rosuav@gmail.com> - 2012-07-14 01:36 +1000
                Re: code review rusi <rustompmody@gmail.com> - 2012-07-13 09:24 -0700
                Re: code review Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2012-07-13 16:39 -0400
                Re: code review Duncan Booth <duncan.booth@invalid.invalid> - 2012-07-16 10:43 +0000
                Re: code review Ben Finney <ben+python@benfinney.id.au> - 2012-07-16 21:34 +1000
                Re: code review Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-07-17 10:54 +0000
                Re: code review Terry Reedy <tjreedy@udel.edu> - 2012-07-13 19:09 -0400
                Re: code review Ian Kelly <ian.g.kelly@gmail.com> - 2012-07-14 03:26 -0600
                Re: code review Terry Reedy <tjreedy@udel.edu> - 2012-07-14 16:42 -0400
                Re: code review rusi <rustompmody@gmail.com> - 2012-06-30 21:07 -0700
                Re: code review Chris Angelico <rosuav@gmail.com> - 2012-07-01 14:20 +1000
                Re: code review Ben Finney <ben+python@benfinney.id.au> - 2012-07-01 17:28 +1000
                Re: code review Thomas Jollans <t@jollybox.de> - 2012-07-01 09:46 +0200
                Re: code review HoneyMonster <nobody@someplace.invalid> - 2012-07-01 20:53 +0000
                Re: code review Devin Jeanpierre <jeanpierreda@gmail.com> - 2012-07-01 05:18 -0400
                Re: code review Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-02 00:41 +0000
                Re: code review Devin Jeanpierre <jeanpierreda@gmail.com> - 2012-07-01 21:40 -0400
                Re: code review Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2012-07-01 13:41 -0400
                Re: code review John O'Hagan <research@johnohagan.com> - 2012-07-02 14:43 +1000
                Re: Re: code review Evan Driscoll <driscoll@cs.wisc.edu> - 2012-06-30 23:45 -0500
                Re: Re: code review Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-07-01 08:57 +0200
                Re: code review Alister <alister.ware@ntlworld.com> - 2012-07-01 09:54 +0000
                Re: Re: code review Evan Driscoll <driscoll@cs.wisc.edu> - 2012-07-01 10:48 -0500
                Re: Re: code review lars van gemerden <lars@rational-it.com> - 2012-07-06 04:22 -0700
                Re: Re: code review lars van gemerden <lars@rational-it.com> - 2012-07-06 04:22 -0700
                Re: code review Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-06 13:58 +0000
                Re: code review Roy Smith <roy@panix.com> - 2012-07-13 08:32 -0700
                Re: code review Evan Driscoll <driscoll@cs.wisc.edu> - 2012-06-30 23:57 -0500
                Re: code review Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-07-01 09:04 +0200
                Re: code review Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-01 02:06 +0000
                Re: code review Chris Angelico <rosuav@gmail.com> - 2012-07-01 12:20 +1000
                Re: code review Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-01 04:17 +0000
                Re: code review Chris Angelico <rosuav@gmail.com> - 2012-07-01 14:23 +1000
                Re: code review Steven D'Aprano <steve+usenet@pearwood.info> - 2012-07-01 06:27 +0000
                Re: code review Chris Angelico <rosuav@gmail.com> - 2012-07-01 16:33 +1000
                Re: code review Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-02 01:28 +0000
                Re: code review Devin Jeanpierre <jeanpierreda@gmail.com> - 2012-07-01 21:50 -0400
                Re: code review Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-02 07:29 +0000
                Re: code review Chris Angelico <rosuav@gmail.com> - 2012-07-02 12:04 +1000
                Re: code review Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-02 08:11 +0000
                Re: code review Chris Angelico <rosuav@gmail.com> - 2012-07-02 18:20 +1000
                Re: code review Rick Johnson <rantingrickjohnson@gmail.com> - 2012-07-02 08:57 -0700
                Re: code review Chris Angelico <rosuav@gmail.com> - 2012-07-03 02:42 +1000
                Re: code review Rick Johnson <rantingrickjohnson@gmail.com> - 2012-07-02 11:22 -0700
                Re: code review Thomas Jollans <t@jollybox.de> - 2012-07-02 21:06 +0200
                Re: code review Rick Johnson <rantingrickjohnson@gmail.com> - 2012-07-02 12:35 -0700
                Re: code review Chris Angelico <rosuav@gmail.com> - 2012-07-03 07:57 +1000
                Re: code review Neil Cerutti <neilc@norwich.edu> - 2012-07-03 12:19 +0000
                Re: code review Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2012-07-02 01:20 -0400
                Re: code review Thomas Jollans <t@jollybox.de> - 2012-07-02 16:41 +0200
                Re: code review Terry Reedy <tjreedy@udel.edu> - 2012-07-02 11:33 -0400
                Re: code review Thomas Jollans <t@jollybox.de> - 2012-07-01 09:35 +0200
                Re: code review Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-02 00:43 +0000
                Re: code review Thomas Jollans <t@jollybox.de> - 2012-07-02 16:26 +0200
                Re: code review Rick Johnson <rantingrickjohnson@gmail.com> - 2012-07-02 08:16 -0700
                Re: code review Chris Angelico <rosuav@gmail.com> - 2012-07-03 02:55 +1000
                Re: code review Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-03 00:57 +0000
                Re: code review Chris Angelico <rosuav@gmail.com> - 2012-07-03 11:22 +1000
                Re: code review John O'Hagan <research@johnohagan.com> - 2012-07-03 12:25 +1000
                Re: code review Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-03 04:11 +0000
                Re: code review Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2012-07-03 02:09 -0400
                Re: code review Roy Smith <roy@panix.com> - 2012-07-03 08:33 -0400
                Re: code review Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-07-03 16:53 +0100
                Re: code review Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2012-07-03 17:32 -0400
                Re: code review rusi <rustompmody@gmail.com> - 2012-07-02 22:10 -0700
                Re: code review Ben Finney <ben+python@benfinney.id.au> - 2012-07-03 15:46 +1000
                Re: code review John O'Hagan <research@johnohagan.com> - 2012-07-04 00:59 +1000
                Re: code review Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-07-03 16:50 +0100
                Re: code review Paul Rudin <paul.nospam@rudin.co.uk> - 2012-07-04 10:29 +0100
                Re: code review Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-07-04 17:25 +0100
                Re: code review Chris Angelico <rosuav@gmail.com> - 2012-07-04 01:53 +1000
                Re: code review Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-07-03 17:05 +0100
                Re: code review Dave Angel <d@davea.name> - 2012-07-03 16:13 -0400
                Re: code review Chris Angelico <rosuav@gmail.com> - 2012-07-04 07:54 +1000
                Re: code review Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-07-04 09:28 +0100
                Re: code review rusi <rustompmody@gmail.com> - 2012-06-30 19:37 -0700
                Re: code review Chris Angelico <rosuav@gmail.com> - 2012-07-01 09:25 +1000
                Re: code review Thomas Jollans <t@jollybox.de> - 2012-07-01 01:50 +0200
                Re: code review "Martin P. Hellwig" <martin.hellwig@gmail.com> - 2012-06-30 14:48 -0700
                Re: code review Ian Kelly <ian.g.kelly@gmail.com> - 2012-07-02 13:16 -0600
            Re: code review Alister <alister.ware@ntlworld.com> - 2012-06-30 20:25 +0000
          Re: code review Kushal Kumaran <kushal.kumaran+python@gmail.com> - 2012-07-03 23:23 +0530
            Re: code review John Gordon <gordon@panix.com> - 2012-07-03 18:18 +0000
              Re: code review Ian Kelly <ian.g.kelly@gmail.com> - 2012-07-03 12:27 -0600
              Re: code review Chris Angelico <rosuav@gmail.com> - 2012-07-04 07:51 +1000
          Re: code review Ian Kelly <ian.g.kelly@gmail.com> - 2012-07-03 12:19 -0600
          Re: code review kushal.kumaran+python@gmail.com - 2012-07-04 08:27 +0530
          Re: code review Chris Angelico <rosuav@gmail.com> - 2012-07-04 13:53 +1000
          Re: code review Simon Cropper <simoncropper@fossworkflowguides.com> - 2012-07-04 14:55 +1000
          Re: code review "Littlefield, Tyler" <tyler@tysdomain.com> - 2012-07-03 23:39 -0600
            Re: code review alex23 <wuwei23@gmail.com> - 2012-07-03 23:17 -0700
              Re: code review rusi <rustompmody@gmail.com> - 2012-07-04 00:05 -0700
          Apology for OT posts (was: code review) John O'Hagan <research@johnohagan.com> - 2012-07-06 12:06 +1000
          Re: Apology for OT posts Simon Cropper <simoncropper@fossworkflowguides.com> - 2012-07-06 15:30 +1000
          Re: Apology for OT posts Chris Angelico <rosuav@gmail.com> - 2012-07-06 17:45 +1000
          Re: Apology for OT posts Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-07-06 10:37 +0100

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