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To: python-list@python.org
From: Terry Reedy <tjreedy@udel.edu>
Subject: Re: Extension of while syntax
Date: Thu, 11 Dec 2014 22:00:44 -0500
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On 12/11/2014 9:21 PM, Nelson Crosby wrote:
> I was thinking a bit about the following pattern:
>
> value = get_some_value()
> while value in undesired_values:
>      value = get_some_value()

This is do_while or do_until.  In Python, write it as do_until in this form.

while True:
     value = get_some_value()
     if value not in undesired_values:
         break

> I've always hated code that looks like this. Partly due to the repetition,
> but partly also due to the fact that without being able to immediately
 > recognise this pattern, it isn't very readable.

The repetitiion is easily eliminated.

> value = get_some_value() while value in undesired_values()

Forget this, or anything like it, as a 'serious' proposal.

-- 
Terry Jan Reedy