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Re: checking if a list is empty

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On 11/05/2011 20:13, Hans Georg Schaathun wrote:
> On Wed, 11 May 2011 12:17:33 -0700, Ethan Furman
>    <ethan@stoneleaf.us>  wrote:
> :  'if li' *is* KISS.
>
> It /might/ be in some contexts, but a priori it is not, as it
> superimposes a truth value on a data type which is otherwise
> a pretty accurate model of real objects (outside python).
>
> One principle of object oriented programming is to bestow the
> objects with properties reflecting known properties from the
> domain being modelled.  Lists do not have truth values in the
> application domain, and therefore truth values in the
> implementation domain is complicated.
>
Exactly. Its just a convention.  If it exists, its true, if if doesn't 
its false.

In the "real world"  lists of zero items do not exist.
You don't go shopping with a shopping list of zero items.
You don't take a journey going nowhere.
You wouldn't have a party and invite nobody.
What kind of building is one with zero floors?
Would you have an Aircraft Carrier with no aircraft?

Oh Wait - the UK has one of those coming into service soon.

Regards

Ian

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Re: checking if a list is empty Terry Reedy <tjreedy@udel.edu> - 2011-05-06 15:31 -0400
  Re: checking if a list is empty harrismh777 <harrismh777@charter.net> - 2011-05-06 14:49 -0500
    Re: checking if a list is empty Adam Tauno Williams <awilliam@whitemice.org> - 2011-05-06 16:05 -0400
      Re: checking if a list is empty Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-05-07 02:49 +0000
        Re: checking if a list is empty Hans Georg Schaathun <hg@schaathun.net> - 2011-05-11 10:14 +0100
          Re: checking if a list is empty Laurent Claessens <moky.math@gmail.com> - 2011-05-11 11:48 +0200
            Re: checking if a list is empty Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-05-11 11:14 +0000
              Re: checking if a list is empty Laurent Claessens <moky.math@gmail.com> - 2011-05-11 13:45 +0200
              Re: checking if a list is empty Laurent Claessens <moky.math@gmail.com> - 2011-05-11 13:45 +0200
          Re: checking if a list is empty Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-05-11 13:36 +0000
            Re: checking if a list is empty Hans Georg Schaathun <hg@schaathun.net> - 2011-05-11 15:00 +0100
              Re: checking if a list is empty Chris Angelico <rosuav@gmail.com> - 2011-05-12 00:46 +1000
              Re: checking if a list is empty Ethan Furman <ethan@stoneleaf.us> - 2011-05-11 08:53 -0700
              RE: checking if a list is empty "Prasad, Ramit" <ramit.prasad@jpmchase.com> - 2011-05-11 13:50 -0400
                Re: checking if a list is empty Hans Georg Schaathun <hg@schaathun.net> - 2011-05-11 19:15 +0100
                RE: checking if a list is empty "Prasad, Ramit" <ramit.prasad@jpmchase.com> - 2011-05-11 14:59 -0400
                Re: checking if a list is empty Hans Georg Schaathun <hg@schaathun.net> - 2011-05-11 20:08 +0100
                Re: checking if a list is empty Ethan Furman <ethan@stoneleaf.us> - 2011-05-11 12:17 -0700
                Re: checking if a list is empty Hans Georg Schaathun <hg@schaathun.net> - 2011-05-11 20:13 +0100
                Re: checking if a list is empty Ian <hobson42@gmail.com> - 2011-05-11 22:02 +0100
                Re: checking if a list is empty Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-05-11 21:47 +0000
                Re: checking if a list is empty Steven Howe <howe.steven@gmail.com> - 2011-05-11 15:09 -0700
                Re: checking if a list is empty harrismh777 <harrismh777@charter.net> - 2011-05-11 17:38 -0500
                Re: checking if a list is empty harrismh777 <harrismh777@charter.net> - 2011-05-11 18:12 -0500
                Re: checking if a list is empty Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-05-12 01:07 +0000
                Re: checking if a list is empty Hans Georg Schaathun <hg@schaathun.net> - 2011-05-12 06:21 +0100
                Re: checking if a list is empty Chris Angelico <rosuav@gmail.com> - 2011-05-12 13:51 +1000
                Re: checking if a list is empty Ethan Furman <ethan@stoneleaf.us> - 2011-05-12 07:02 -0700
                Re: checking if a list is empty Chris Angelico <rosuav@gmail.com> - 2011-05-13 00:13 +1000
              Re: checking if a list is empty Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2011-05-12 11:08 +1200
    Re: checking if a list is empty Chris Rebert <clp2@rebertia.com> - 2011-05-06 13:46 -0700
    Re: checking if a list is empty Chris Angelico <rosuav@gmail.com> - 2011-05-07 10:51 +1000
    Re: checking if a list is empty Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-05-07 08:28 +0000
      Re: checking if a list is empty harrismh777 <harrismh777@charter.net> - 2011-05-07 22:50 -0500
        Re: checking if a list is empty Ethan Furman <ethan@stoneleaf.us> - 2011-05-07 21:57 -0700
          Re: checking if a list is empty Hans Georg Schaathun <hg@schaathun.net> - 2011-05-11 11:47 +0100
            Re: checking if a list is empty Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-05-11 13:45 +0000
              Re: checking if a list is empty Hans Georg Schaathun <hg@schaathun.net> - 2011-05-11 15:34 +0100
                Re: checking if a list is empty Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-05-11 16:26 +0000
                Re: checking if a list is empty Hans Georg Schaathun <hg@schaathun.net> - 2011-05-11 19:05 +0100
                RE: checking if a list is empty "Prasad, Ramit" <ramit.prasad@jpmchase.com> - 2011-05-11 14:44 -0400
                Re: checking if a list is empty Hans Georg Schaathun <hg@schaathun.net> - 2011-05-11 20:26 +0100
                Learning new languages (was: checking if a list is empty) Teemu Likonen <tlikonen@iki.fi> - 2011-05-12 06:37 +0300
                Re: checking if a list is empty Chris Torek <nospam@torek.net> - 2011-05-11 19:05 +0000
                Re: checking if a list is empty Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-05-11 21:42 +0000
                Re: checking if a list is empty Hans Georg Schaathun <hg@schaathun.net> - 2011-05-12 07:23 +0100
                Re: checking if a list is empty Ian Kelly <ian.g.kelly@gmail.com> - 2011-05-11 10:31 -0600
                Re: checking if a list is empty Hans Georg Schaathun <hg@schaathun.net> - 2011-05-11 18:46 +0100
            Re: checking if a list is empty "D'Arcy J.M. Cain" <darcy@druid.net> - 2011-05-11 10:33 -0400
              Re: checking if a list is empty Redcat <redcat@catfolks.net> - 2011-05-11 15:31 +0000
              Re: checking if a list is empty Hans Georg Schaathun <hg@schaathun.net> - 2011-05-11 18:44 +0100
              Re: checking if a list is empty harrismh777 <harrismh777@charter.net> - 2011-05-11 16:24 -0500
                Re: checking if a list is empty alex23 <wuwei23@gmail.com> - 2011-05-11 20:31 -0700
                Re: checking if a list is empty harrismh777 <harrismh777@charter.net> - 2011-05-11 22:53 -0500
                Re: checking if a list is empty Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-05-12 06:13 +0000
                Re: checking if a list is empty "rurpy@yahoo.com" <rurpy@yahoo.com> - 2011-05-12 10:42 -0700
                Re: checking if a list is empty harrismh777 <harrismh777@charter.net> - 2011-05-13 14:41 -0500
                Re: checking if a list is empty Ian Kelly <ian.g.kelly@gmail.com> - 2011-05-13 14:21 -0600
                Re: checking if a list is empty harrismh777 <harrismh777@charter.net> - 2011-05-13 19:48 -0500
                Re: checking if a list is empty Ian Kelly <ian.g.kelly@gmail.com> - 2011-05-13 19:52 -0600
                Re: checking if a list is empty harrismh777 <harrismh777@charter.net> - 2011-05-13 23:47 -0500
                Re: checking if a list is empty Ian Kelly <ian.g.kelly@gmail.com> - 2011-05-14 00:14 -0600
                Re: checking if a list is empty Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2011-05-14 14:32 +1200
                Re: checking if a list is empty Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2011-05-14 14:26 +1200
                Re: checking if a list is empty Hans Georg Schaathun <hg@schaathun.net> - 2011-05-12 07:13 +0100
                Re: checking if a list is empty Ben Finney <ben+python@benfinney.id.au> - 2011-05-12 16:46 +1000
                Re: checking if a list is empty Hans Georg Schaathun <hg@schaathun.net> - 2011-05-12 08:28 +0100
                Re: checking if a list is empty Ben Finney <ben+python@benfinney.id.au> - 2011-05-12 17:37 +1000
                Re: checking if a list is empty "D'Arcy J.M. Cain" <darcy@druid.net> - 2011-05-12 01:49 -0400
                Re: checking if a list is empty Hans Georg Schaathun <hg@schaathun.net> - 2011-05-12 07:21 +0100
                Re: checking if a list is empty Chris Angelico <rosuav@gmail.com> - 2011-05-12 22:16 +1000
                Re: checking if a list is empty Hans Georg Schaathun <hg@schaathun.net> - 2011-05-12 13:43 +0100
                Re: checking if a list is empty Chris Angelico <rosuav@gmail.com> - 2011-05-12 23:20 +1000
                Re: checking if a list is empty Hans Georg Schaathun <hg@schaathun.net> - 2011-05-13 09:47 +0100
        Re: checking if a list is empty Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-05-08 14:07 +0000
          Re: checking if a list is empty Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2011-05-08 18:59 +0300
          Re: checking if a list is empty Terry Reedy <tjreedy@udel.edu> - 2011-05-08 18:41 -0400
          Re: checking if a list is empty Michael Torrie <torriem@gmail.com> - 2011-05-08 21:31 -0600
          Re: checking if a list is empty harrismh777 <harrismh777@charter.net> - 2011-05-08 22:33 -0500
            Re: checking if a list is empty Ian Kelly <ian.g.kelly@gmail.com> - 2011-05-08 22:34 -0600
              Re: checking if a list is empty harrismh777 <harrismh777@charter.net> - 2011-05-09 16:58 -0500
                Re: checking if a list is empty Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-05-09 23:34 +0000
                Re: checking if a list is empty Ben Finney <ben+python@benfinney.id.au> - 2011-05-10 09:54 +1000
                Re: checking if a list is empty harrismh777 <harrismh777@charter.net> - 2011-05-09 19:10 -0500
                Re: checking if a list is empty harrismh777 <harrismh777@charter.net> - 2011-05-09 19:19 -0500
            Re: checking if a list is empty James Mills <prologic@shortcircuit.net.au> - 2011-05-09 14:46 +1000
          Re: checking if a list is empty harrismh777 <harrismh777@charter.net> - 2011-05-08 22:56 -0500
          Re: checking if a list is empty Terry Reedy <tjreedy@udel.edu> - 2011-05-09 17:30 -0400
          Re: checking if a list is empty Chris Torek <nospam@torek.net> - 2011-05-12 03:49 +0000

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