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Re: Python handles globals badly.

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On Fri, Sep 11, 2015 at 9:15 AM, Chris Angelico <rosuav@gmail.com> wrote:
> On Sat, Sep 12, 2015 at 1:03 AM, Ian Kelly <ian.g.kelly@gmail.com> wrote:
>>> There's also a bunch of specialised and complicated rules for what happens
>>> if you make a star import ("from module import *") inside a function, or
>>> call eval or exec without specifying a namespace. Both of these things are
>>> now illegal in Python 3.
>>
>> Huh?
>>
>>>>> exec("x = 42")
>>>>> x
>> 42
>>>>> exec("x = 43", None, None)
>>>>> x
>> 43
>>
>> That's in Python 3.4.0. Maybe I don't understand what you mean by
>> "without specifying a namespace".
>
> *inside a function*
>
>>>> def f():
> ...    exec("x = 42")
> ...    print(x)
> ...
>>>> x = 231
>>>> f()
> 231

Ah, I didn't parse the "inside a function" as applying to that clause,
but even so, I don't see in what way that is "now illegal". For
example:

>>> x = 231
>>> def f():
...   exec("print(x); x = 42; print(x)")
...   print(x)
...
>>> f()
231
42
231

The exec still happily runs; it's just using its own private locals namespace.

Tangent: does the help for exec need to be updated? It currently reads:

    The globals and locals are dictionaries, defaulting to the current
    globals and locals.  If only globals is given, locals defaults to it.

Which would seem to indicate that if called from within a function
with no globals or locals, the locals from the function would be used.

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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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