Re: Python handles globals badly.

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From	Ian Kelly <ian.g.kelly@gmail.com>
Date	Fri, 11 Sep 2015 10:27:57 -0600
Subject	Re: Python handles globals badly.
To	Python <python-list@python.org>
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On Fri, Sep 11, 2015 at 10:04 AM, Chris Angelico <rosuav@gmail.com> wrote:
> On Sat, Sep 12, 2015 at 1:57 AM,  <random832@fastmail.us> wrote:
>> On Fri, Sep 11, 2015, at 11:55, Chris Angelico wrote:
>>> On Sat, Sep 12, 2015 at 1:49 AM, Ian Kelly <ian.g.kelly@gmail.com> wrote:
>>> > Ah, that makes sense. It's writing into the dict that is created and
>>> > returned by locals(), but not actually updating the frame locals which
>>> > are the source of truth.
>>>
>>> Yeah... but it only makes sense to people who understand the
>>> implementation. It's certainly not a logical and sane behaviour that
>>> would be worth documenting and using.
>>
>> What else would you document? Reading from them is a reasonable thing to
>> do, and works. Writing to them is a reasonable thing to want to do, but
>> won't work, so you need to document that it doesn't work.
>
> Documenting that "it doesn't work" seems fine. Documenting the
> specific behaviour (that it gives you a sort of "shadow" locals, into
> which you can write, but which won't persist past the execution of
> that block of code) seems pointless. Especially since this behaviour
> is implementation-dependent anyway.

It's documented in the standard library docs:
https://docs.python.org/3.4/library/functions.html#exec

I think that's probably sufficient.

Thread

Re: Python handles globals badly. tdev@freenet.de - 2015-09-10 15:25 -0700
  Re: Python handles globals badly. Emile van Sebille <emile@fenx.com> - 2015-09-10 15:40 -0700
  Re: Python handles globals badly. Ian Kelly <ian.g.kelly@gmail.com> - 2015-09-10 18:35 -0600
    Re: Python handles globals badly. Marko Rauhamaa <marko@pacujo.net> - 2015-09-11 07:34 +0300
      Re: Python handles globals badly. Chris Angelico <rosuav@gmail.com> - 2015-09-11 14:59 +1000
        Re: Python handles globals badly. Marko Rauhamaa <marko@pacujo.net> - 2015-09-11 08:15 +0300
          Re: Python handles globals badly. Chris Angelico <rosuav@gmail.com> - 2015-09-11 15:25 +1000
          Re: Python handles globals badly. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-12 03:43 +0100
      Re: Python handles globals badly. Ian Kelly <ian.g.kelly@gmail.com> - 2015-09-10 23:07 -0600
        Re: Python handles globals badly. Marko Rauhamaa <marko@pacujo.net> - 2015-09-11 08:27 +0300
      Re: Python handles globals badly. Rustom Mody <rustompmody@gmail.com> - 2015-09-11 00:39 -0700
    Re: Python handles globals badly. Steven D'Aprano <steve@pearwood.info> - 2015-09-11 18:42 +1000
      Re: Python handles globals badly. Chris Angelico <rosuav@gmail.com> - 2015-09-11 19:16 +1000
      Re: Python handles globals badly. Ian Kelly <ian.g.kelly@gmail.com> - 2015-09-11 09:03 -0600
        Re: Python handles globals badly. Steven D'Aprano <steve@pearwood.info> - 2015-09-12 17:00 +1000
      Re: Python handles globals badly. Chris Angelico <rosuav@gmail.com> - 2015-09-12 01:15 +1000
      Re: Python handles globals badly. Ian Kelly <ian.g.kelly@gmail.com> - 2015-09-11 09:27 -0600
      Re: Python handles globals badly. Chris Angelico <rosuav@gmail.com> - 2015-09-12 01:44 +1000
      Re: Python handles globals badly. Ian Kelly <ian.g.kelly@gmail.com> - 2015-09-11 09:49 -0600
      Re: Python handles globals badly. Chris Angelico <rosuav@gmail.com> - 2015-09-12 01:55 +1000
      Re: Python handles globals badly. random832@fastmail.us - 2015-09-11 11:57 -0400
        Re: Python handles globals badly. Rustom Mody <rustompmody@gmail.com> - 2015-09-11 09:08 -0700
      Re: Python handles globals badly. Chris Angelico <rosuav@gmail.com> - 2015-09-12 02:04 +1000
      Re: Python handles globals badly. Ian Kelly <ian.g.kelly@gmail.com> - 2015-09-11 10:27 -0600
      Re: Python handles globals badly. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-12 03:51 +0100
  Re: Python handles globals badly. MRAB <python@mrabarnett.plus.com> - 2015-09-11 02:17 +0100
  Re: Python handles globals badly. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-12 03:27 +0100

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