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Re: Evaluation order

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Date Fri, 10 Jul 2015 12:02:41 +1000
Subject Re: Evaluation order
From Chris Angelico <rosuav@gmail.com>
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On Fri, Jul 10, 2015 at 10:10 AM, candide <c.candide@laposte.net> wrote:
> The official doc explains that :
>
> Python evaluates expressions from left to right.
>
> cf. https://docs.python.org/3.3/reference/expressions.html#evaluation-order
>
>
> But consider the following snippet :
>
>
>>>> t=[2020, 42, 2015]
>>>> t*(1+int(bool(t.sort())))
> [42, 2015, 2020]
>>>>
>
>
> Is there not some contradiction with left-right evalutation?

I'm not sure what contradiction you're referring to, here. The
evaluation that you're pointing out says, as Terry showed via the
disassembly, that Python's first action is to look up the name 't' and
grab a reference to whatever object it points to. The execution of
t.sort() has to happen before the multiplication, because of the
parentheses.

ChrisA

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Thread

Evaluation order candide <c.candide@laposte.net> - 2015-07-09 17:10 -0700
  Re: Evaluation order Terry Reedy <tjreedy@udel.edu> - 2015-07-09 21:45 -0400
  Re: Evaluation order Chris Angelico <rosuav@gmail.com> - 2015-07-10 12:02 +1000
    Re: Evaluation order candide <c.candide@laposte.net> - 2015-07-10 05:04 -0700
      Re: Evaluation order Ned Batchelder <ned@nedbatchelder.com> - 2015-07-10 05:19 -0700
      Re: Evaluation order Terry Reedy <tjreedy@udel.edu> - 2015-07-10 08:27 -0400
      Re: Evaluation order Chris Angelico <rosuav@gmail.com> - 2015-07-11 00:27 +1000
      Re: Evaluation order Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-07-10 15:49 +0100

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