Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.python > #110405

Re: Operator Precedence/Boolean Logic

Path csiph.com!fu-berlin.de!uni-berlin.de!not-for-mail
From Antoon Pardon <antoon.pardon@rece.vub.ac.be>
Newsgroups comp.lang.python
Subject Re: Operator Precedence/Boolean Logic
Date Thu, 23 Jun 2016 13:15:32 +0200
Lines 35
Message-ID <mailman.68.1466680570.11516.python-list@python.org> (permalink)
References <15997174-44d5-431c-8f90-a8d700921820@googlegroups.com> <56ecacd4-cc17-48ec-9830-57c8113d16f6@googlegroups.com> <YoudnV5Wro07zvbKnZ2dnUU7-b3NnZ2d@giganews.com> <576b5ea3$0$1595$c3e8da3$5496439d@news.astraweb.com> <576B96C0.2040106@rece.vub.ac.be> <mailman.56.1466668786.11516.python-list@python.org> <87a8icgw0d.fsf@elektro.pacujo.net> <4e388a43-0191-4a48-8517-3ee3bdc50910@googlegroups.com> <871t3ogti9.fsf@elektro.pacujo.net> <576BAB88.3030407@rece.vub.ac.be> <mailman.62.1466674276.11516.python-list@python.org> <87oa6sfczf.fsf@elektro.pacujo.net> <576BBFFF.3070504@rece.vub.ac.be> <mailman.67.1466679335.11516.python-list@python.org> <878txwf9w5.fsf@elektro.pacujo.net> <576BC4D4.7030509@rece.vub.ac.be>
Mime-Version 1.0
Content-Type text/plain; charset=utf-8
Content-Transfer-Encoding 7bit
X-Trace news.uni-berlin.de PQuyqflFfuJrnojoMm+4rwU+dpTWZNvmupRyHVmXA5Dg==
Return-Path <antoon.pardon@rece.vub.ac.be>
X-Original-To python-list@python.org
Delivered-To python-list@mail.python.org
X-Spam-Status OK 0.002
X-Spam-Evidence '*H*': 1.00; '*S*': 0.00; 'else:': 0.03; 'method.': 0.05; 'received:134': 0.05; 'except:': 0.07; 'raises': 0.07; 'check.': 0.09; 'python': 0.10; 'exception': 0.13; 'def': 0.13; '12:59': 0.16; 'boolean': 0.16; 'distinction': 0.16; 'emptiness': 0.16; 'received:ac.be': 0.16; 'received:io': 0.16; 'received:psf.io': 0.16; "wouldn't": 0.16; 'try:': 0.18; 'decide': 0.23; 'this:': 0.23; 'header:In-Reply-To:1': 0.24; 'header:User- Agent:1': 0.26; "doesn't": 0.26; 'least': 0.27; 'function': 0.28; 'behaviour': 0.29; 'declared': 0.29; 'raise': 0.29; 'subject:/': 0.30; 'received:be': 0.30; 'maybe': 0.33; 'point': 0.33; 'class': 0.33; 'except': 0.34; 'could': 0.35; 'false': 0.35; 'something': 0.35; 'cases': 0.36; 'to:addr:python-list': 0.36; 'subject:: ': 0.37; 'say': 0.37; 'wrong': 0.38; 'anything': 0.38; 'to:addr:python.org': 0.40; 'where': 0.40; 'effective': 0.63; 'between': 0.65; 'talking': 0.67; 'worth': 0.67; 'pardon': 0.84; 'schreef': 0.84; 'canonical': 0.91
X-IronPort-Anti-Spam-Filtered true
X-IronPort-Anti-Spam-Result ArQIAHYeUleGuA9G/2dsb2JhbABehFsBMbxfhhICggABAQEBAQFmhG0BAQQjVRELGgIFFgsCAgkDAgECAUUTBgICiCuxTY0+g1sBAQgCJYEBhSaETYUMgjWCWQWYRYFXjE2JM4Vpj1JUg3BsAYoRAQEB
User-Agent Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Icedove/38.8.0
In-Reply-To <878txwf9w5.fsf@elektro.pacujo.net>
X-BeenThere python-list@python.org
X-Mailman-Version 2.1.22
Precedence list
List-Id General discussion list for the Python programming language <python-list.python.org>
List-Unsubscribe <https://mail.python.org/mailman/options/python-list>, <mailto:python-list-request@python.org?subject=unsubscribe>
List-Archive <http://mail.python.org/pipermail/python-list/>
List-Post <mailto:python-list@python.org>
List-Help <mailto:python-list-request@python.org?subject=help>
List-Subscribe <https://mail.python.org/mailman/listinfo/python-list>, <mailto:python-list-request@python.org?subject=subscribe>
X-Mailman-Original-Message-ID <576BC4D4.7030509@rece.vub.ac.be>
X-Mailman-Original-References <15997174-44d5-431c-8f90-a8d700921820@googlegroups.com> <56ecacd4-cc17-48ec-9830-57c8113d16f6@googlegroups.com> <YoudnV5Wro07zvbKnZ2dnUU7-b3NnZ2d@giganews.com> <576b5ea3$0$1595$c3e8da3$5496439d@news.astraweb.com> <576B96C0.2040106@rece.vub.ac.be> <mailman.56.1466668786.11516.python-list@python.org> <87a8icgw0d.fsf@elektro.pacujo.net> <4e388a43-0191-4a48-8517-3ee3bdc50910@googlegroups.com> <871t3ogti9.fsf@elektro.pacujo.net> <576BAB88.3030407@rece.vub.ac.be> <mailman.62.1466674276.11516.python-list@python.org> <87oa6sfczf.fsf@elektro.pacujo.net> <576BBFFF.3070504@rece.vub.ac.be> <mailman.67.1466679335.11516.python-list@python.org> <878txwf9w5.fsf@elektro.pacujo.net>
Xref csiph.com comp.lang.python:110405

Show key headers only | View raw

Op 23-06-16 om 12:59 schreef Marko Rauhamaa:
> Antoon Pardon <antoon.pardon@rece.vub.ac.be>:
>
>> Op 23-06-16 om 11:53 schreef Marko Rauhamaa:
>> Maybe something like this:
>>
>> def empty(sq):
>>     try:
>>         iter(sq).next()
>>     except StopIteration:
>>         return False
>>     except:
>>         raise TypeError
>>     else:
>>         return True
> That may or may not be as effective as a boolean check. The point is,
> Python has already declared that __bool__ is the canonical emptiness
> checker. You could even say that it's the principal purpose of the
> __bool__ method.

I think it is wrong to say __bool__ is the canonical emptiness checker.
It can be used for anything where you somehow think it is reasonable
to make a distinction between truthy and falsy. Even when talking
about emptyness doesn't make sense.

The function above at least raises an exception in a lot of cases
where the class provides booly behaviour yet emptyness wouldn't make
sense.

Would it be worth while? That you have to decide for yourself.

-- 
Antoon.

Back to comp.lang.python | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Operator Precedence/Boolean Logic Elizabeth Weiss <cake240@gmail.com> - 2016-06-21 20:40 -0700
  Re: Operator Precedence/Boolean Logic Ben Finney <ben+python@benfinney.id.au> - 2016-06-22 13:59 +1000
    Re: Operator Precedence/Boolean Logic Elizabeth Weiss <cake240@gmail.com> - 2016-06-22 21:19 -0700
    Re: Operator Precedence/Boolean Logic Elizabeth Weiss <cake240@gmail.com> - 2016-06-22 21:20 -0700
  Re: Operator Precedence/Boolean Logic Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-06-22 16:02 +1000
  Re: Operator Precedence/Boolean Logic Christian Gollwitzer <auriocus@gmx.de> - 2016-06-22 08:26 +0200
    Re: Operator Precedence/Boolean Logic Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-06-22 10:14 +0300
      Re: Operator Precedence/Boolean Logic Elizabeth Weiss <cake240@gmail.com> - 2016-06-22 21:21 -0700
  Re: Operator Precedence/Boolean Logic Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-06-22 00:42 -0700
    Re: Operator Precedence/Boolean Logic Larry Hudson <orgnut@yahoo.com> - 2016-06-22 20:12 -0700
      Re: Operator Precedence/Boolean Logic Steven D'Aprano <steve@pearwood.info> - 2016-06-23 13:59 +1000
        Re: Operator Precedence/Boolean Logic Elizabeth Weiss <cake240@gmail.com> - 2016-06-22 21:23 -0700
        Re: Operator Precedence/Boolean Logic Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-06-23 09:58 +0200
          Re: Operator Precedence/Boolean Logic Marko Rauhamaa <marko@pacujo.net> - 2016-06-23 11:16 +0300
            Re: Operator Precedence/Boolean Logic Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-06-23 01:53 -0700
              Re: Operator Precedence/Boolean Logic Marko Rauhamaa <marko@pacujo.net> - 2016-06-23 12:10 +0300
                Re: Operator Precedence/Boolean Logic Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-06-23 11:27 +0200
                Re: Operator Precedence/Boolean Logic Marko Rauhamaa <marko@pacujo.net> - 2016-06-23 12:53 +0300
                Re: Operator Precedence/Boolean Logic Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-06-23 12:54 +0200
                Re: Operator Precedence/Boolean Logic Marko Rauhamaa <marko@pacujo.net> - 2016-06-23 13:59 +0300
                Re: Operator Precedence/Boolean Logic Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-06-23 13:15 +0200
                Re: Operator Precedence/Boolean Logic Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-06-23 15:05 +0300
                Re: Operator Precedence/Boolean Logic Chris Angelico <rosuav@gmail.com> - 2016-06-23 22:13 +1000
                Re: Operator Precedence/Boolean Logic Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-06-23 02:44 -0700
                Re: Operator Precedence/Boolean Logic Marko Rauhamaa <marko@pacujo.net> - 2016-06-23 12:57 +0300
                Re: Operator Precedence/Boolean Logic Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-06-24 22:38 -0700
                Re: Operator Precedence/Boolean Logic Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-06-25 09:46 +0300
            Re: Operator Precedence/Boolean Logic Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-06-23 11:01 +0200
          Re: Operator Precedence/Boolean Logic Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-06-23 19:39 +1000
            Re: Operator Precedence/Boolean Logic Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-06-23 12:21 +0200
              Re: Operator Precedence/Boolean Logic Steven D'Aprano <steve@pearwood.info> - 2016-06-23 22:37 +1000
                Re: Operator Precedence/Boolean Logic Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-06-23 15:24 +0200
                Re: Operator Precedence/Boolean Logic Random832 <random832@fastmail.com> - 2016-06-23 09:26 -0400
                Re: Operator Precedence/Boolean Logic Steven D'Aprano <steve@pearwood.info> - 2016-06-24 02:43 +1000
                Re: Operator Precedence/Boolean Logic Chris Angelico <rosuav@gmail.com> - 2016-06-24 01:49 +1000
        Re: Operator Precedence/Boolean Logic Marko Rauhamaa <marko@pacujo.net> - 2016-06-25 11:56 +0300
      Re: Operator Precedence/Boolean Logic Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-06-22 21:47 -0700
        Re: Operator Precedence/Boolean Logic Rustom Mody <rustompmody@gmail.com> - 2016-06-22 22:00 -0700
        Re: Operator Precedence/Boolean Logic Andreas Röhler <andreas.roehler@online.de> - 2016-06-23 08:34 +0200
          Re: Operator Precedence/Boolean Logic Marko Rauhamaa <marko@pacujo.net> - 2016-06-23 09:46 +0300
          Re: Operator Precedence/Boolean Logic Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-06-23 17:05 +1000
            Re: Operator Precedence/Boolean Logic Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-06-23 10:17 +0200
              Re: Operator Precedence/Boolean Logic Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-06-23 18:48 +1000
                Re: Operator Precedence/Boolean Logic Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-06-23 11:23 +0200
                Re: Operator Precedence/Boolean Logic Chris Angelico <rosuav@gmail.com> - 2016-06-23 21:45 +1000
                Re: Operator Precedence/Boolean Logic Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-06-23 14:08 +0200
                Re: Operator Precedence/Boolean Logic Andreas Röhler <andreas.roehler@online.de> - 2016-06-23 14:22 +0200
            Re: Operator Precedence/Boolean Logic Andreas Röhler <andreas.roehler@online.de> - 2016-06-23 10:23 +0200
            Re: Operator Precedence/Boolean Logic Andreas Röhler <andreas.roehler@online.de> - 2016-06-23 10:32 +0200
              Re: Operator Precedence/Boolean Logic Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-06-23 19:17 +1000
                Re: Operator Precedence/Boolean Logic Marko Rauhamaa <marko@pacujo.net> - 2016-06-23 12:46 +0300
                Re: Operator Precedence/Boolean Logic Andreas Röhler <andreas.roehler@online.de> - 2016-06-23 12:19 +0200
                Re: Operator Precedence/Boolean Logic Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2016-06-26 11:01 +1200
                Re: Operator Precedence/Boolean Logic Rustom Mody <rustompmody@gmail.com> - 2016-06-29 03:21 -0700
                Re: Operator Precedence/Boolean Logic Chris Angelico <rosuav@gmail.com> - 2016-06-29 21:06 +1000
                Re: Operator Precedence/Boolean Logic Steven D'Aprano <steve@pearwood.info> - 2016-06-29 23:08 +1000
                Re: Operator Precedence/Boolean Logic Rustom Mody <rustompmody@gmail.com> - 2016-06-29 06:30 -0700
                Re: Operator Precedence/Boolean Logic Steven D'Aprano <steve@pearwood.info> - 2016-06-30 09:40 +1000
                Re: Operator Precedence/Boolean Logic Rustom Mody <rustompmody@gmail.com> - 2016-06-30 09:01 -0700
                Re: Operator Precedence/Boolean Logic Steven D'Aprano <steve@pearwood.info> - 2016-07-01 03:22 +1000
                Re: Operator Precedence/Boolean Logic Rustom Mody <rustompmody@gmail.com> - 2016-07-15 22:48 -0700
                Re: Operator Precedence/Boolean Logic Rustom Mody <rustompmody@gmail.com> - 2016-07-15 22:58 -0700
                Re: Operator Precedence/Boolean Logic Steven D'Aprano <steve@pearwood.info> - 2016-07-16 19:14 +1000
                Re: Operator Precedence/Boolean Logic Steven D'Aprano <steve@pearwood.info> - 2016-07-16 20:16 +1000
                Re: Operator Precedence/Boolean Logic Chris Angelico <rosuav@gmail.com> - 2016-07-16 20:46 +1000
                Re: Operator Precedence/Boolean Logic Steven D'Aprano <steve@pearwood.info> - 2016-07-16 21:02 +1000
                Re: Operator Precedence/Boolean Logic Chris Angelico <rosuav@gmail.com> - 2016-07-17 00:26 +1000
                Re: Operator Precedence/Boolean Logic Rustom Mody <rustompmody@gmail.com> - 2016-07-16 05:33 -0700
                Re: Operator Precedence/Boolean Logic Steven D'Aprano <steve@pearwood.info> - 2016-07-17 02:27 +1000
                Re: Operator Precedence/Boolean Logic MRAB <python@mrabarnett.plus.com> - 2016-07-16 17:58 +0100
                Re: Operator Precedence/Boolean Logic Rustom Mody <rustompmody@gmail.com> - 2016-07-16 20:43 -0700
                Re: Operator Precedence/Boolean Logic Chris Angelico <rosuav@gmail.com> - 2016-07-17 14:05 +1000
                Re: Operator Precedence/Boolean Logic Rustom Mody <rustompmody@gmail.com> - 2016-07-16 23:44 -0700
                Re: Operator Precedence/Boolean Logic Rustom Mody <rustompmody@gmail.com> - 2016-07-16 23:59 -0700
                Re: Operator Precedence/Boolean Logic Chris Angelico <rosuav@gmail.com> - 2016-07-17 17:33 +1000
                Re: Operator Precedence/Boolean Logic Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-07-17 00:44 -0700
                Re: Operator Precedence/Boolean Logic Steven D'Aprano <steve@pearwood.info> - 2016-07-17 20:04 +1000
                Re: Operator Precedence/Boolean Logic Steven D'Aprano <steve@pearwood.info> - 2016-07-17 21:02 +1000
                Re: Operator Precedence/Boolean Logic Rustom Mody <rustompmody@gmail.com> - 2016-07-17 08:00 -0700
                Re: Operator Precedence/Boolean Logic Steven D'Aprano <steve@pearwood.info> - 2016-07-18 01:58 +1000
                Re: Operator Precedence/Boolean Logic Steven D'Aprano <steve@pearwood.info> - 2016-07-18 02:01 +1000
                Re: Operator Precedence/Boolean Logic Chris Angelico <rosuav@gmail.com> - 2016-07-17 03:06 +1000
                Re: Operator Precedence/Boolean Logic Rustom Mody <rustompmody@gmail.com> - 2016-07-16 05:15 -0700
                Re: Operator Precedence/Boolean Logic Steven D'Aprano <steve@pearwood.info> - 2016-07-17 02:36 +1000
                Re: Operator Precedence/Boolean Logic Grant Edwards <grant.b.edwards@gmail.com> - 2016-06-29 15:00 +0000
                Re: Operator Precedence/Boolean Logic Jon Ribbens <jon+usenet@unequivocal.eu> - 2016-06-29 15:05 +0000
                Re: Operator Precedence/Boolean Logic Steven D'Aprano <steve@pearwood.info> - 2016-06-30 09:44 +1000
                Re: Operator Precedence/Boolean Logic Andreas Röhler <andreas.roehler@online.de> - 2016-06-23 11:51 +0200
        Re: Operator Precedence/Boolean Logic Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-06-23 17:20 +1000
        Re: Operator Precedence/Boolean Logic Random832 <random832@fastmail.com> - 2016-06-23 09:18 -0400
      Re: Operator Precedence/Boolean Logic Christian Gollwitzer <auriocus@gmx.de> - 2016-06-23 09:11 +0200
    Re: Operator Precedence/Boolean Logic Elizabeth Weiss <cake240@gmail.com> - 2016-06-22 21:22 -0700
  Fwd: Operator Precedence/Boolean Logic Jorge Gimeno <jlgimeno71@gmail.com> - 2016-06-21 20:56 -0700
  Re: Operator Precedence/Boolean Logic Random832 <random832@fastmail.com> - 2016-06-22 10:10 -0400
  Re: Operator Precedence/Boolean Logic Erik <python@lucidity.plus.com> - 2016-06-22 20:43 +0100

csiph-web