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From: Devin Jeanpierre <jeanpierreda@gmail.com>
Date: Fri, 26 Oct 2012 19:41:52 -0400
Subject: Re: while expression feature proposal
To: Cameron Simpson <cs@zip.com.au>
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Xref: csiph.com comp.lang.python:32246

On Fri, Oct 26, 2012 at 6:03 PM, Cameron Simpson <cs@zip.com.au> wrote:
> Any doco would need to make it clear that no order of operation is
> implied, so that this:
>
>   x = 1
>   y = (2 as x) + x
>
> does not have a defined answer; might be 2, might be 3. Just like any
> other function call with side effects.

But function calls with side effects _do_ have a defined order of
evaluation. Left to right. And the answer should be 4.

http://docs.python.org/reference/expressions.html#evaluation-order

>>> def set_(d, k, v):
...     d[k] = v
...     return v
...
>>> d = {}
>>> set_(d, 'x', 1)
1
>>> set_(d, 'y', set_(d, 'x', 2) + d['x'])
4

-- Devin