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Groups > comp.lang.python > #32239

Re: while expression feature proposal

Date 2012-10-27 09:03 +1100
From Cameron Simpson <cs@zip.com.au>
Subject Re: while expression feature proposal
References <7xlietjjsd.fsf@ruckus.brouhaha.com>
Newsgroups comp.lang.python
Message-ID <mailman.2909.1351289024.27098.python-list@python.org> (permalink)

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On 26Oct2012 09:10, Paul Rubin <no.email@nospam.invalid> wrote:
| However, if the "as" can be part of an expression as in Chris Angelico's
| post, Chris's suggestion
| 
|      while (client.spop("profile_ids") as profile_id) is not None:
|          print profile_id
| 
| looks good to me.

Now this pulls me from a -0 to a +0.5.

Instead of burdening the control constructs with further structure, make
"as" a binding operation for keeping intermediate results from expressions.

It will work anywhere an expression is allowed, and superficially
doesn't break stuff that exists if "as" has the lowest precedence.

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.

Speaking for myself (of course!), I definitely prefer this to adding
"as" as a post expression struction on if/while/etc.

I'm not +1 because to my mind it still presents a way for
assignment/binding to not be glaringly obvious at the left hand side of
an expression.

It would probably mean folding the except/with "as" uses back into
expressions and out of the control-structural part of the grammar. I can't
see that that would actually break any existing code though - anyone else?

Cheers,
-- 
Cameron Simpson <cs@zip.com.au>

UNIX was not designed to stop you from doing stupid things, because that
would also stop you from doing clever things.   - Doug Gwyn

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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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