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Re: while expression feature proposal

References (8 earlier) <k6c8kh$lqj$1@r03.glglgl.gl> <f3e3c344-8a7d-46f7-b499-144775c7f9aa@googlegroups.com> <7x7gqdzs1i.fsf@ruckus.brouhaha.com> <CAPTjJmqhw8w2G=vqHt=LpWejLFG16npgZk6CbBBG0d1CMnhAoA@mail.gmail.com> <CABicbJJ073VyhsikKsqF-AhLcriAKdfd8qoTAO3B0OAyYUT-mg@mail.gmail.com>
Date 2012-10-27 11:42 +1100
Subject Re: while expression feature proposal
From Chris Angelico <rosuav@gmail.com>
Newsgroups comp.lang.python
Message-ID <mailman.2926.1351298548.27098.python-list@python.org> (permalink)

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On Sat, Oct 27, 2012 at 10:19 AM, Devin Jeanpierre
<jeanpierreda@gmail.com> wrote:
> On Fri, Oct 26, 2012 at 2:23 AM, Chris Angelico <rosuav@gmail.com> wrote:
>> while (client.spop("profile_ids") as profile_id) is not None:
>>     print profile_id
>>
>> Why is everyone skirting around C-style assignment expressions as
>> though they're simultaneously anathema and the goal? :)
>
> Why should these two statements behave differently? :(
>
>     with foo() as bar: bar.baz()
>     with (foo() as bar): bar.baz()
>
> I don't understand why everyone is so attached to this "as" syntax.
> It's confusing because it behaves subtly differently than how it works
> in "with", and it puts the variable on the wrong side of the
> assignment operator.
>
> (I've always been partial to ":=", personally.)

I'm not attached to "as", myself. It puts the variable at the wrong
end, and feels backward compared to a convention that exists elsewhere
in the language (regular variable assignment). This is a much stronger
backwardness issue than the Python ternary operator (which is only
backward in comparison to other languages).

Personally, I'm quite happy with assignment itself being an
expression. But since that's unlikely to be directly accepted in
Python, I would be looking for something as general as possible -
something that can truly be used _anywhere_ - rather than a specific
while-statement enhancement. Capturing partial expression results is
an extremely convenient thing to do.

ChrisA

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Thread

Re: while expression feature proposal Ian Kelly <ian.g.kelly@gmail.com> - 2012-10-24 16:54 -0600
  Re: while expression feature proposal Paul Rubin <no.email@nospam.invalid> - 2012-10-24 16:08 -0700
    Re: while expression feature proposal Ian Kelly <ian.g.kelly@gmail.com> - 2012-10-24 17:39 -0600
      Re: while expression feature proposal Thomas Rachel <nutznetz-0c1b6768-bfa9-48d5-a470-7603bd3aa915@spamschutz.glglgl.de> - 2012-10-25 09:21 +0200
        Re: while expression feature proposal Thomas Rachel <nutznetz-0c1b6768-bfa9-48d5-a470-7603bd3aa915@spamschutz.glglgl.de> - 2012-10-25 12:12 +0200
        Re: while expression feature proposal Ian Kelly <ian.g.kelly@gmail.com> - 2012-10-25 10:36 -0600
          Re: while expression feature proposal Thomas Rachel <nutznetz-0c1b6768-bfa9-48d5-a470-7603bd3aa915@spamschutz.glglgl.de> - 2012-10-25 22:49 +0200
            Re: while expression feature proposal Dan Loewenherz <dloewenherz@gmail.com> - 2012-10-25 22:12 -0700
              Re: while expression feature proposal Paul Rubin <no.email@nospam.invalid> - 2012-10-25 23:06 -0700
                Re: while expression feature proposal Chris Angelico <rosuav@gmail.com> - 2012-10-26 17:23 +1100
                Re: while expression feature proposal Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-10-26 09:43 +0000
                Re: while expression feature proposal Dan Loewenherz <dloewenherz@gmail.com> - 2012-10-26 08:29 -0700
                Re: while expression feature proposal Ian Kelly <ian.g.kelly@gmail.com> - 2012-10-26 09:42 -0600
                Re: while expression feature proposal Paul Rubin <no.email@nospam.invalid> - 2012-10-26 09:10 -0700
                Re: while expression feature proposal Cameron Simpson <cs@zip.com.au> - 2012-10-27 09:03 +1100
                Re: while expression feature proposal Ian Kelly <ian.g.kelly@gmail.com> - 2012-10-26 16:48 -0600
                Re: while expression feature proposal Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-10-27 00:07 +0000
                Re: while expression feature proposal Paul Rubin <no.email@nospam.invalid> - 2012-10-26 20:43 -0700
                Re: while expression feature proposal Tim Chase <sed@thechases.com> - 2012-10-26 18:26 -0500
                Re: while expression feature proposal Devin Jeanpierre <jeanpierreda@gmail.com> - 2012-10-26 19:41 -0400
                Re: while expression feature proposal Devin Jeanpierre <jeanpierreda@gmail.com> - 2012-10-26 19:19 -0400
                Re: while expression feature proposal Chris Angelico <rosuav@gmail.com> - 2012-10-27 11:42 +1100
              Re: while expression feature proposal Devin Jeanpierre <jeanpierreda@gmail.com> - 2012-10-26 19:12 -0400
                Re: while expression feature proposal Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-10-27 00:18 +0000
                Re: while expression feature proposal Devin Jeanpierre <jeanpierreda@gmail.com> - 2012-10-26 20:27 -0400
                Re: while expression feature proposal Tim Chase <python.list@tim.thechases.com> - 2012-10-27 14:15 -0500
              Re: while expression feature proposal Devin Jeanpierre <jeanpierreda@gmail.com> - 2012-10-26 19:51 -0400
        Re: while expression feature proposal Ian Kelly <ian.g.kelly@gmail.com> - 2012-10-25 10:47 -0600
    Re: while expression feature proposal Paul Rudin <paul.nospam@rudin.co.uk> - 2012-10-25 10:35 +0100

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