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Re: Python handles globals badly.

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Date Mon, 14 Sep 2015 10:30:18 +0200
From Antoon Pardon <antoon.pardon@rece.vub.ac.be>
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Subject Re: Python handles globals badly.
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Op 12-09-15 om 05:48 schreef Steven D'Aprano:
> I believe I already acknowledged that assignment-as-expression was fine if
> it avoided the = versus == error, from the perspective of avoiding errors.
> But from the perspective of a clean and logical programming model, perhaps
> not so much. Assignment is imperative, not functional, and requiring it to
> return a result is somewhat unclean.

I thought practicallity beats purity? AFAICS python doesn't use such a clean
and logical programming model and it isn't given much critique over it.
So I don't think it is fair to critique assignment as an expression because
of this aspect.

> Look at it this way: suppose you had a robot servant that always, without
> fail or misunderstanding, did what you instructed. There are broadly two
> sorts of things that you can give as instructions: questions, and commands.
> Questions always require an answer: "What's the length of this list?" is
> functional. Commands are imperative, not functional, and don't necessarily
> require an answer: "Move the small red pyramid onto the large green cube."
> Some commands arguable might require an answer, but arguable they are
> better served by an out-of-band error condition (an exception). *Requiring*
> all commands to give an answer is silly, given that the robot servant is
> infallible.

But we are not talking about all commands, we are just talking about assignments.
Sure an assignment has a side effect. But so has ls.pop(). So something having
a side-effect and a value is not unheard of even within a python context.

-- 
Antoon Pardon

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Re: Python handles globals badly. tdev@freenet.de - 2015-09-02 11:47 -0700
  Re: Python handles globals badly. tdev@freenet.de - 2015-09-02 12:32 -0700
  Re: Python handles globals badly. Emile van Sebille <emile@fenx.com> - 2015-09-02 12:34 -0700
  Re: Python handles globals badly. Ian Kelly <ian.g.kelly@gmail.com> - 2015-09-02 13:38 -0600
  Re: Python handles globals badly. "Sven R. Kunze" <srkunze@mail.de> - 2015-09-02 22:08 +0200
  Re: Python handles globals badly. MRAB <python@mrabarnett.plus.com> - 2015-09-02 21:22 +0100
  Re: Python handles globals badly. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-02 22:19 +0100
  Re: Python handles globals badly. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-03 02:16 +0100
  Re: Python handles globals badly. Steven D'Aprano <steve@pearwood.info> - 2015-09-03 11:49 +1000
  Re: Python handles globals badly. Vladimir Ignatov <kmisoft@gmail.com> - 2015-09-04 20:05 -0400
  Re: Python handles globals badly. Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-09-08 10:40 +0200
  Re: Python handles globals badly. Vladimir Ignatov <kmisoft@gmail.com> - 2015-09-08 07:55 -0400
  Re: Python handles globals badly. Akira Li <4kir4.1i@gmail.com> - 2015-09-08 15:35 +0300
  Re: Python handles globals badly. Mario Figueiredo <marfig@gmx.com> - 2015-09-08 14:05 +0100
  Re: Python handles globals badly. Ian Kelly <ian.g.kelly@gmail.com> - 2015-09-08 08:31 -0600
    Re: Python handles globals badly. Steven D'Aprano <steve@pearwood.info> - 2015-09-09 01:56 +1000
      Re: Python handles globals badly. Michael Torrie <torriem@gmail.com> - 2015-09-08 17:55 -0600
        Re: Python handles globals badly. Steven D'Aprano <steve@pearwood.info> - 2015-09-09 13:23 +1000
          Re: Python handles globals badly. Christian Gollwitzer <auriocus@gmx.de> - 2015-09-09 18:09 +0200
            Re: Python handles globals badly. Steven D'Aprano <steve@pearwood.info> - 2015-09-10 03:22 +1000
              Re: Python handles globals badly. Chris Angelico <rosuav@gmail.com> - 2015-09-10 03:27 +1000
              Re: Python handles globals badly. William Ray Wing <wrw@mac.com> - 2015-09-09 13:59 -0400
              Re: Python handles globals badly. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-09 20:20 +0100
                Re: Python handles globals badly. Peter Pearson <pkpearson@nowhere.invalid> - 2015-09-10 20:49 +0000
              Re: Python handles globals badly. MRAB <python@mrabarnett.plus.com> - 2015-09-09 20:22 +0100
              Re: Python handles globals badly. Chris Angelico <rosuav@gmail.com> - 2015-09-10 05:27 +1000
      Re: Python handles globals badly. Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-09-09 12:42 +0200
      Re: Python handles globals badly. Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2015-09-09 09:33 -0400
  Re: Python handles globals badly. random832@fastmail.us - 2015-09-08 12:13 -0400
  Re: Python handles globals badly. MRAB <python@mrabarnett.plus.com> - 2015-09-08 18:41 +0100
  Re: Python handles globals badly. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-08 23:41 +0100
  Re: Python handles globals badly. MRAB <python@mrabarnett.plus.com> - 2015-09-09 00:20 +0100
  Re: Python handles globals badly. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-09 00:32 +0100
  Re: Python handles globals badly. Random832 <random832@fastmail.com> - 2015-09-08 20:02 -0400
    Re: Python handles globals badly. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-11 10:23 +0200
  Re: Python handles globals badly. Mario Figueiredo <marfig@gmx.com> - 2015-09-09 02:09 +0100
    Re: Python handles globals badly. Steven D'Aprano <steve@pearwood.info> - 2015-09-10 03:55 +1000
      Re: Python handles globals badly. Laura Creighton <lac@openend.se> - 2015-09-09 20:05 +0200
      Re: Python handles globals badly. Emile van Sebille <emile@fenx.com> - 2015-09-09 11:23 -0700
        Re: Python handles globals badly. Steven D'Aprano <steve@pearwood.info> - 2015-09-10 22:20 +1000
      Re: Python handles globals badly. "Sven R. Kunze" <srkunze@mail.de> - 2015-09-09 20:26 +0200
        Re: Python handles globals badly. Steven D'Aprano <steve@pearwood.info> - 2015-09-11 01:50 +1000
      Re: Python handles globals badly. random832@fastmail.us - 2015-09-09 14:59 -0400
        Re: Python handles globals badly. Steven D'Aprano <steve@pearwood.info> - 2015-09-11 01:59 +1000
          Re: Python handles globals badly. random832@fastmail.us - 2015-09-10 12:31 -0400
            Re: Python handles globals badly. Steven D'Aprano <steve@pearwood.info> - 2015-09-11 04:13 +1000
              Re: Python handles globals badly. Chris Angelico <rosuav@gmail.com> - 2015-09-11 04:33 +1000
              Re: Python handles globals badly. Jussi Piitulainen <harvesting@makes.email.invalid> - 2015-09-10 22:11 +0300
              Re: Python handles globals badly. random832@fastmail.us - 2015-09-10 16:30 -0400
          Re: Python handles globals badly. Chris Angelico <rosuav@gmail.com> - 2015-09-11 02:48 +1000
          Re: Python handles globals badly. alister <alister.nospam.ware@ntlworld.com> - 2015-09-10 19:56 +0000
          Re: Python handles globals badly. random832@fastmail.us - 2015-09-10 16:07 -0400
          Re: Python handles globals badly. Chris Angelico <rosuav@gmail.com> - 2015-09-11 11:35 +1000
          Re: Python handles globals badly. Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-09-11 12:19 +0200
            Re: Python handles globals badly. Marko Rauhamaa <marko@pacujo.net> - 2015-09-11 14:59 +0300
              Re: Python handles globals badly. Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-09-14 09:13 +0200
      Re: Python handles globals badly. Chris Angelico <rosuav@gmail.com> - 2015-09-10 05:00 +1000
      Re: Python handles globals badly. Laura Creighton <lac@openend.se> - 2015-09-09 21:14 +0200
      Re: Python handles globals badly. Chris Angelico <rosuav@gmail.com> - 2015-09-10 05:18 +1000
        Re: Python handles globals badly. Steven D'Aprano <steve@pearwood.info> - 2015-09-10 22:18 +1000
          Re: Python handles globals badly. jkn <jkn_gg@nicorp.f9.co.uk> - 2015-09-10 08:09 -0700
          Re: Python handles globals badly. rurpy@yahoo.com - 2015-09-10 12:04 -0700
            Re: Python handles globals badly. Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2015-09-10 20:33 -0400
            Re: Python handles globals badly. Gene Heskett <gheskett@wdtv.com> - 2015-09-10 22:19 -0400
            Re: Python handles globals badly. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-12 03:35 +0100
            Re: Python handles globals badly. Mario Figueiredo <marfig@gmx.com> - 2015-09-12 05:11 +0100
            Re: Python handles globals badly. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-12 05:38 +0100
            Re: Python handles globals badly. Mario Figueiredo <marfig@gmx.com> - 2015-09-12 16:52 +0100
            Re: Python handles globals badly. Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2015-09-12 12:24 -0400
            Re: Python handles globals badly. Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2015-09-12 12:29 -0400
            Re: Python handles globals badly. MRAB <python@mrabarnett.plus.com> - 2015-09-12 18:09 +0100
            Re: Python handles globals badly. Mario Figueiredo <marfig@gmx.com> - 2015-09-12 22:57 +0100
            Re: Python handles globals badly. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-12 23:05 +0100
            Re: Python handles globals badly. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-12 23:07 +0100
      Re: Python handles globals badly. "Sven R. Kunze" <srkunze@mail.de> - 2015-09-09 21:21 +0200
      Re: Python handles globals badly. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-09 20:24 +0100
      Re: Python handles globals badly. Mario Figueiredo <marfig@gmx.com> - 2015-09-09 20:57 +0100
      Re: Python handles globals badly. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-09 21:15 +0100
      Re: Python handles globals badly. Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-09-10 09:27 +0200
        Re: Python handles globals badly. Marko Rauhamaa <marko@pacujo.net> - 2015-09-10 10:49 +0300
      Re: Python handles globals badly. Michael Torrie <torriem@gmail.com> - 2015-09-10 08:21 -0600
      Re: Python handles globals badly. Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-09-11 09:28 +0200
        Re: Python handles globals badly. Steven D'Aprano <steve@pearwood.info> - 2015-09-12 13:48 +1000
          Re: Python handles globals badly. Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-09-14 10:30 +0200
            Re: Python handles globals badly. Steven D'Aprano <steve@pearwood.info> - 2015-09-16 11:13 +1000
              Re: Python handles globals badly. Steven D'Aprano <steve@pearwood.info> - 2015-09-16 11:20 +1000
                Re: Python handles globals badly. Chris Angelico <rosuav@gmail.com> - 2015-09-16 11:58 +1000
              Re: Python handles globals badly. Random832 <random832@fastmail.com> - 2015-09-15 21:54 -0400
              Re: Python handles globals badly. Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-09-16 10:51 +0200
      Re: Python handles globals badly. random832@fastmail.us - 2015-09-11 08:50 -0400
  Re: Python handles globals badly. Ben Finney <ben+python@benfinney.id.au> - 2015-09-09 11:26 +1000
  Re: Python handles globals badly. Chris Angelico <rosuav@gmail.com> - 2015-09-09 11:41 +1000
  Re: Python handles globals badly. Mario Figueiredo <marfig@gmx.com> - 2015-09-09 03:43 +0100
  Re: Python handles globals badly. Chris Angelico <rosuav@gmail.com> - 2015-09-09 13:03 +1000
  Re: Python handles globals badly. Ben Finney <ben+python@benfinney.id.au> - 2015-09-09 15:53 +1000

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