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Date: Sun, 24 Feb 2013 08:44:53 -0600
From: Tim Chase <python.list@tim.thechases.com>
To: Chris Angelico <rosuav@gmail.com>
Subject: Re: [Python-ideas] iterable.__unpack__ method
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Xref: csiph.com comp.lang.python:39747

On 2013-02-25 01:19, Chris Angelico wrote:
> >>>      command, subcommand = next(iterargs), next(iterargs)
> >>
> >>
> >> Err.... is there a language guarantee of the order of evaluation
> >> in a tuple, or is this just a "CPython happens to evaluate
> >> independent expressions left-to-right"? This is totally broken
> >> if the next() calls could be done in either order.
> >
> > It's a language guarantee.
> >
> > http://docs.python.org/2/reference/expressions.html#evaluation-order
> 
> Ah, so it is. My bad, sorry! In that case, sure, this works. It
> still violates DRY though, naming the iterable twice and relying on
> the reader noticing that that means "take two off this one". But
> that's a much weaker concern.

Your DRY/readability concern might then be addressed by writing it as

  from itertools import islice
  # ...
  command, subcommand = islice(iterargs, 2)

(sorry if this was already addressed in the python-ideas@ thread,
since I'm not subscribed there and it looks like discussion migrated
to python-list@).

-tkc