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Re: Operator Precedence/Boolean Logic

From Antoon Pardon <antoon.pardon@rece.vub.ac.be>
Newsgroups comp.lang.python
Subject Re: Operator Precedence/Boolean Logic
Date 2016-06-23 12:54 +0200
Message-ID <mailman.67.1466679335.11516.python-list@python.org> (permalink)
References (8 earlier) <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>

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Op 23-06-16 om 11:53 schreef Marko Rauhamaa:
> Antoon Pardon <antoon.pardon@rece.vub.ac.be>:
>
>> Op 23-06-16 om 11:10 schreef Marko Rauhamaa:
>>> The __len__ method is not guaranteed to execute in O(1). See:
>>>
>>>    <URL: https://docs.python.org/3/reference/datamodel.html?highlig
>>>    ht=__len__#object.__len__>
>> As far as I can see, neither is the __bool__ method.
> Correct, but in the absence of an __empty__ method, __bool__ gives the
> class the best opportunity to check for emptiness quickly.
>
> This is not only a theoretical concern. It's quite common for data
> structures not to maintain an element count because it's extra baggage
> that's not always needed and any application could keep a track of.
> However, an emptiness check is often trivial.

Maybe something like this:

def empty(sq):
    try:
        iter(sq).next()
    except StopIteration:
        return False
    except:
        raise TypeError
    else:
        return True

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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

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