Re: Python handles globals badly.

Date	2015-09-11 12:19 +0200
From	Antoon Pardon <antoon.pardon@rece.vub.ac.be>
Subject	Re: Python handles globals badly.
References	(9 earlier) <55f072aa$0$1669$c3e8da3$5496439d@news.astraweb.com> <mailman.281.1441825163.8327.python-list@python.org> <55f1a8df$0$1660$c3e8da3$5496439d@news.astraweb.com> <1441902711.3168172.380049449.32E41922@webmail.messagingengine.com> <CAPTjJmpngxHPM6_WMyGGizwMww1LKvFtAM5bXyf6inzUJK9Yiw@mail.gmail.com>
Newsgroups	comp.lang.python
Message-ID	<mailman.365.1441966789.8327.python-list@python.org> (permalink)

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Op 10-09-15 om 18:48 schreef Chris Angelico:
> I'm not sure what the point would be of having an expression that
> doesn't return a value. The point of assignment-as-an-expression is
> that you can do other things with the result:
>
> while ((ch=getchar()) != EOF)
>
> In Python, we have a couple of cases where that's done with the 'as' keyword:
>
> with open(fn) as in_file:
>
> except KeyError as e:
>
> and there've been proposals now and then to have the same thing added
> to if and while, which actually isn't hard:
>
> while getchar() as ch:

I just don't get why people want to introduce special cases in python.
Why allow such a construct only in while and if? Why not just allow
it generally as an assignment expression?

Why not allow:

  while (f(x) as fx) > 5:
    proces(fx)

or

  if check(nextvalue() as new):
    treat(new)

One of the things I don't like about python is the limitation of the
slice syntax. I have been in situations where the natural thing to
do was write a method that takes a slice as a parameter and
have it called like: for key, value in Tree.items(lowkey:highkey).

But that doesn't work because slice notation is only allowed in
a subscription context.

It is kind of frustrating when you see something in the language
you think useful, to then notice the language doesn't allow you
to use in the context you need/want it.

At this moment I feel that introducing the "as v" possibily only
in while and if statements would mainly enlargen my frustration.

-- 
Antoon Pardon

Thread

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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