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| From | Terry Reedy <tjreedy@udel.edu> |
| Subject | Re: checking if a list is empty |
| Date | Sun, 08 May 2011 18:41:20 -0400 |
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On 5/8/2011 10:07 AM, Steven D'Aprano wrote: > Because the test of "is this nothing, or something?" is a common, useful > test: Because inductive algorithms commonly branch on 'input is something' (not done, change args toward 'nothing'and recurse or iterate) versus 'input is nothing (done, return base expression). > 0 (nothing) vs 1, 2, 3, ... (something) > empty list versus non-empty list > empty dict versus non-empty dict > empty set versus non-empty set > empty string versus non-empty string and non-inductive algorithms also branch on the same question. > no search results returned versus some search results returned > no network connection available versus some network connection available > no food in the cupboard versus food in the cupboard > > This is a fundamental distinction which is very useful in practice. Definitely. Python commonly hides the distinction inside of iterators called by for statememts, but StopIteration is understood as 'collection is empty'. An I suspect something vs. nothing is also the most common overt condition in if and while statements. -- Terry Jan Reedy
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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 Thomas Rachel <nutznetz-0c1b6768-bfa9-48d5-a470-7603bd3aa915@spamschutz.glglgl.de> - 2011-05-22 22:41 +0200
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 Ian <hobson42@gmail.com> - 2011-05-22 10:20 +0100
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 John J Lee <jjl@pobox.com> - 2011-05-21 15:46 +0100
Re: checking if a list is empty Emile van Sebille <emile@fenx.com> - 2011-05-21 08:52 -0700
Re: checking if a list is empty Terry Reedy <tjreedy@udel.edu> - 2011-05-21 16:11 -0400
Re: checking if a list is empty rusi <rustompmody@gmail.com> - 2011-05-21 20:02 -0700
Re: checking if a list is empty Chris Angelico <rosuav@gmail.com> - 2011-05-22 13:52 +1000
Re: checking if a list is empty rusi <rustompmody@gmail.com> - 2011-05-21 21:32 -0700
Re: checking if a list is empty Chris Angelico <rosuav@gmail.com> - 2011-05-22 15:16 +1000
Re: checking if a list is empty Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-05-22 01:02 +0000
Re: checking if a list is empty Chris Angelico <rosuav@gmail.com> - 2011-05-22 12:56 +1000
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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