Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!feeder.erje.net!eu.feeder.erje.net!xlned.com!feeder1.xlned.com!news2.euro.net!newsgate.cistron.nl!newsgate.news.xs4all.nl!post.news.xs4all.nl!not-for-mail
Return-Path: <python-python-list@m.gmane.org>
X-Original-To: python-list@python.org
Delivered-To: python-list@mail.python.org
X-Spam-Status: OK 0.036
X-Spam-Evidence: '*H*': 0.93; '*S*': 0.00; 'attribute': 0.07; 'lookup': 0.09; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'jan': 0.12; '*must*': 0.16; 'choose,': 0.16; 'ignoring': 0.16; 'lookups.': 0.16; 'received:80.91.229.3': 0.16; 'received:plane.gmane.org': 0.16; 'reedy': 0.16; 'roy': 0.16; 'wrote:': 0.18; '>>>': 0.22; 'header:User-Agent:1': 0.23; 'logical': 0.24; 'replace': 0.24; 'header:X-Complaints-To:1': 0.27; 'header:In-Reply-To:1': 0.27; 'am,': 0.29; 'url:wiki': 0.31; 'url:wikipedia': 0.31; 'url:org': 0.36; 'two': 0.37; 'being': 0.38; 'to:addr:python-list': 0.38; 'fact': 0.38; 'pm,': 0.38; 'rather': 0.38; 'flow': 0.39; 'to:addr:python.org': 0.39; 'received:org': 0.40; 'how': 0.40; 'easy': 0.60; 'received:173': 0.61; "you're": 0.61; 'first': 0.61; 'act': 0.63; 'name': 0.63; 'response.': 0.68; 'smith': 0.68; 'article': 0.77; 'beside': 0.84; 'given.': 0.84; 'premature': 0.84; 'received:fios.verizon.net': 0.84; 'wish,': 0.91
X-Injected-Via-Gmane: http://gmane.org/
To: python-list@python.org
From: Terry Jan Reedy <tjreedy@udel.edu>
Subject: Re: Short-circuit Logic
Date: Sun, 26 May 2013 17:28:56 -0400
References: <5f101d70-e51f-4531-9153-c92ee2486fd9@googlegroups.com> <mailman.2196.1369599562.3114.python-list@python.org> <roy-31D5CD.16222626052013@news.panix.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
X-Gmane-NNTP-Posting-Host: pool-173-75-251-66.phlapa.fios.verizon.net
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/20130509 Thunderbird/17.0.6
In-Reply-To: <roy-31D5CD.16222626052013@news.panix.com>
X-BeenThere: python-list@python.org
X-Mailman-Version: 2.1.15
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.2206.1369603740.3114.python-list@python.org>
Lines: 29
NNTP-Posting-Host: 2001:888:2000:d::a6
X-Trace: 1369603740 news.xs4all.nl 15896 [2001:888:2000:d::a6]:33211
X-Complaints-To: abuse@xs4all.nl
Xref: csiph.com comp.lang.python:46127

On 5/26/2013 4:22 PM, Roy Smith wrote:
> In article <mailman.2196.1369599562.3114.python-list@python.org>,
>   Terry Jan Reedy <tjreedy@udel.edu> wrote:
>
>> On 5/26/2013 7:11 AM, Ahmed Abdulshafy wrote:
>>
>>>        if not allow_zero and abs(x) < sys.float_info.epsilon:
>>>                   print("zero is not allowed")
>>
>> The reason for the order is to do the easy calculation first and the
>> harder one only if the first passes.
>
> This is a particularly egregious case of premature optimization.  You're
> worried about how long it takes to execute abs(x)?  That's silly.

This is a particularly egregious case of premature response. You're 
ignoring an extra name lookup and two extra attribute lookups. That's silly.

That's beside the fact that one *must* choose, so any difference is a 
reason to act rather than being frozen like Buridan's ass.
http://en.wikipedia.org/wiki/Buridan%27s_ass

If you wish, replace 'The reason' with 'A reason'. I also the logical 
flow as better with the order given.