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To: python-list@python.org
From: Dan Sommers <dan@tombstonezero.net>
Subject: Re: idiomatic analogue of Perl's: while (<>) { ... }
Date: Fri, 2 Sep 2011 02:32:17 +0000 (UTC)
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On Thu, 01 Sep 2011 16:02:54 +1000, Steven D'Aprano wrote:

> On Thu, 1 Sep 2011 02:56 pm Sahil Tandon wrote:

>> # process input, line-by-line, and print responses after parsing input
>> while 1:
>>   rval = parse(raw_input())
>>   if rval == None:
>>     print('foo')
>>   else:
>>     print('bar')
>> %%

> "while True" is considered slightly more idiomatic (readable), but
> otherwise, that seems fine.

Arguably more readable, but arguably less idomatic, is to describe the
actual condition that controls the loop in a string (non-empty strings
are equivalent to True in this context):

while "there is more input":
    rval = parse(raw_input())
    if real is None:
        print('foo')
    else:
        print('bar')

(Although now that I've said that, this looks like an infinite loop
unless parse, raw_input, or print raises an exception.)

Dan