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Date: Wed, 24 Oct 2012 16:54:32 -0500
From: Tim Chase <python.list@tim.thechases.com>
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To: Ian Kelly <ian.g.kelly@gmail.com>
Subject: Re: while expression feature proposal
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On 10/24/12 16:34, Ian Kelly wrote:
> On Wed, Oct 24, 2012 at 2:40 PM, Dan Loewenherz <dloewenherz@gmail.com> wrote:
>> So I'm sure a lot of you have run into the following pattern. I use it
>> all the time and it always has felt a bit awkward due to the duplicate
>> variable assignment.
>>
>> VAR = EXPR
>> while VAR:
>>     BLOCK
>>     VAR = EXPR
> 
> The idiomatic way to do this is:
> 
> while True:
>     VAR = EXPR
>     if not VAR:
>         break
>     BLOCK

It may be idiomatic, but that doesn't stop it from being pretty
ugly.  I must say I really like the parity of Dan's

  while EXPR as VAR:
     BLOCK

proposal with the "with" statement.  It also doesn't fall prey to
the "mistaken-assignment vs. intentional-assignment" found in most
C-like languages.  I could see a pretty reasonable PEP coming from this.

-tkc