Path: csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!news.albasani.net!feeder.erje.net!newsfeed.xs4all.nl!newsfeed5.news.xs4all.nl!xs4all!newsgate.cistron.nl!newsgate.news.xs4all.nl!post.news.xs4all.nl!not-for-mail
Return-Path: <howe.steven@gmail.com>
X-Original-To: python-list@python.org
Delivered-To: python-list@mail.python.org
X-Spam-Status: OK 0.006
X-Spam-Evidence: '*H*': 0.99; '*S*': 0.00; 'wed,': 0.04; '+0100,': 0.07; 'something,': 0.07; 'false,': 0.09; 'length.': 0.09; 'pm,': 0.11; '>>>': 0.12; 'wrote:': 0.14; 'modelled.': 0.16; 'non-empty': 0.16; 'programming': 0.20; 'subject:list': 0.22; 'header:In-Reply- To:1': 0.22; 'values': 0.23; 'oriented': 0.23; 'objects': 0.24; 'object': 0.27; 'lists': 0.28; 'looks': 0.28; 'message- id:@gmail.com': 0.30; 'list': 0.30; 'do.': 0.31; 'determine': 0.31; 'to:addr:python-list': 0.32; '...': 0.32; 'test': 0.33; 'print': 0.35; 'header:User-Agent:1': 0.35; 'usually': 0.36; 'properties': 0.36; 'steven': 0.38; 'received:google.com': 0.38; 'to:addr:python.org': 0.39; 'empty': 0.40; "it's": 0.40; 'header:Received:5': 0.40; 'domain': 0.40; '2011': 0.62; 'truth': 0.65; 'received:74.125.83': 0.69; 'received:home': 0.84
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:message-id:date:from:user-agent:mime-version:to :subject:references:in-reply-to:content-type :content-transfer-encoding; bh=2c3+lFaRV/k1ClG87NMLmK96AP5KNfSKAtJ0TJ2Ct/0=; b=TYPt1LdQEGJycQOjltLE2chdZn9SmwG68Zg+gVnFVc5SkS7Qr0e38Hzh7qU33rMZrA TsVkYHC3WfV/RdHBalcJNhX5qU1gq14yCcnRc+1NUul+IzG1fdMDRWhaIR03W0Gw+VKD 8E5ALEtMFe5BhF+Kq/y/zFlmeXvIpR/y27jHE=
DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:user-agent:mime-version:to:subject:references :in-reply-to:content-type:content-transfer-encoding; b=QMyeYNsi3rd0txLBuGkHnipJdfLk+zlfUEYQTEeJwnkSKX5a5oklMzknKchLj2Iltx uEwwqMU1oaKpOe+O26iqS1tihW0U6tq/0BIRjJi3C3t5DbxHjxXCFM640i2Z/jjhZsfX nbkn5M7hqdLoFu9HtMOBgRZ78Ozn/P4BquVl4=
Date: Wed, 11 May 2011 15:09:51 -0700
From: Steven Howe <howe.steven@gmail.com>
User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.17) Gecko/20110428 Fedora/3.1.10-1.fc14 Thunderbird/3.1.10
MIME-Version: 1.0
To: python-list@python.org
Subject: Re: checking if a list is empty
References: <BANLkTikF18n2dBU6hhFngcAPkE2ZpErVAw@mail.gmail.com>	<BANLkTimWdAijp6vWm9sC_9rFMgpoRf35Hg@mail.gmail.com>	<mailman.1260.1304710333.9059.python-list@python.org>	<9hYwp.5805$xo2.3333@newsfe07.iad>	<mailman.1266.1304712384.9059.python-list@python.org>	<4dc4b351$0$29991$c3e8da3$5496439d@news.astraweb.com>	<uk0q98-446.ln1@svn.schaathun.net>	<4dca90c1$0$29980$c3e8da3$5496439d@news.astraweb.com>	<hchq98-mi6.ln1@svn.schaathun.net>	<mailman.1417.1305136274.9059.python-list@python.org>	<vb0r98-s07.ln1@svn.schaathun.net>	<mailman.1425.1305140738.9059.python-list@python.org>	<vn3r98-k67.ln1@svn.schaathun.net> <4dcb03ef$0$29980$c3e8da3$5496439d@news.astraweb.com>
In-Reply-To: <4dcb03ef$0$29980$c3e8da3$5496439d@news.astraweb.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
X-BeenThere: python-list@python.org
X-Mailman-Version: 2.1.12
Precedence: list
List-Id: General discussion list for the Python programming language <python-list.python.org>
List-Unsubscribe: <http://mail.python.org/mailman/options/python-list>, <mailto:python-list-request@python.org?subject=unsubscribe>
List-Archive: <http://mail.python.org/pipermail/python-list>
List-Post: <mailto:python-list@python.org>
List-Help: <mailto:python-list-request@python.org?subject=help>
List-Subscribe: <http://mail.python.org/mailman/listinfo/python-list>, <mailto:python-list-request@python.org?subject=subscribe>
Newsgroups: comp.lang.python
Message-ID: <mailman.1432.1305151797.9059.python-list@python.org>
Lines: 25
NNTP-Posting-Host: 82.94.164.166
X-Trace: 1305151798 news.xs4all.nl 81481 [::ffff:82.94.164.166]:40512
X-Complaints-To: abuse@xs4all.nl
Xref: x330-a1.tempe.blueboxinc.net comp.lang.python:5167

On 05/11/2011 02:47 PM, Steven D'Aprano wrote:
> On Wed, 11 May 2011 20:13:35 +0100, Hans Georg Schaathun wrote:
>
>> One principle of object oriented programming is to bestow the objects
>> with properties reflecting known properties from the domain being
>> modelled.  Lists do not have truth values in the application domain
> Yes they do. Empty lists are nothing, ergo false, and non-empty lists are
> something, ergo true.
>
>
> >>>  a=[]
> >>>  if a:
> ...     print 'Yes'
> ...
> >>>  a=[1]
> >>>  if a:
> ...     print 'Yes'
> ...
> Yes

Cool; I'd never of thought to try that method to determine if a list was 
empty. I usually test it's length.
This looks faster.