Path: csiph.com!x330-a1.tempe.blueboxinc.net!feeder1.hal-mli.net!feeder.news-service.com!newsfeed.xs4all.nl!newsfeed6.news.xs4all.nl!xs4all!post.news.xs4all.nl!not-for-mail Return-Path: X-Original-To: python-list@python.org Delivered-To: python-list@mail.python.org X-Spam-Status: OK 0.004 X-Spam-Evidence: '*H*': 0.99; '*S*': 0.00; 'seemed': 0.07; 'from:addr:ethan': 0.09; 'from:addr:stoneleaf.us': 0.09; 'from:name:ethan furman': 0.09; 'message-id:@stoneleaf.us': 0.09; 'oh,': 0.09; 'received:gator410.hostgator.com': 0.09; '~ethan~': 0.09; 'wrote:': 0.14; 'furman': 0.16; 'length)': 0.16; 'mylist': 0.16; 'received:72.11': 0.16; 'received:72.11.125': 0.16; 'received:72.11.125.166': 0.16; 'rectangle': 0.16; 'simpler.': 0.16; 'joined': 0.16; 'possibly': 0.16; 'subject:list': 0.22; 'header:In-Reply-To:1': 0.22; 'thu,': 0.22; 'worst': 0.23; 'url:wiki': 0.24; 'subject:?': 0.29; 'depends': 0.29; 'instead,': 0.29; 'list': 0.30; "can't": 0.31; 'to:addr:python-list': 0.32; 'lines': 0.34; 'using': 0.34; 'url:en': 0.35; 'header:User- Agent:1': 0.35; '-0700,': 0.35; 'sense,': 0.35; 'problem.': 0.36; 'be,': 0.38; 'parallel': 0.38; 'steven': 0.38; 'but': 0.38; 'degree': 0.38; 'url:org': 0.38; 'to:addr:python.org': 0.39; 'sets': 0.40; 'header:Received:5': 0.40; 'might': 0.40; '2011': 0.62; 'received:hostgator.com': 0.64; 'received:websitewelcome.com': 0.71; "'em": 0.84; 'dogs': 0.84; 'geometry': 0.84; 'ever!': 0.91 Date: Thu, 12 May 2011 18:04:20 -0700 From: Ethan Furman User-Agent: Thunderbird 1.5.0.10 (Windows/20070221) MIME-Version: 1.0 To: python-list@python.org Subject: Re: list equal to subclass of list? References: <4dcc78b8$0$29980$c3e8da3$5496439d@news.astraweb.com> In-Reply-To: <4dcc78b8$0$29980$c3e8da3$5496439d@news.astraweb.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - gator410.hostgator.com X-AntiAbuse: Original Domain - python.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - stoneleaf.us X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: mail.admailinc.com ([192.168.10.136]) [72.11.125.166]:4504 X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: General discussion list for the Python programming language List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Newsgroups: comp.lang.python Message-ID: Lines: 23 NNTP-Posting-Host: 82.94.164.166 X-Trace: 1305247943 news.xs4all.nl 41117 [::ffff:82.94.164.166]:49838 X-Complaints-To: abuse@xs4all.nl Xref: x330-a1.tempe.blueboxinc.net comp.lang.python:5275 Steven D'Aprano wrote: > On Thu, 12 May 2011 09:43:23 -0700, Ethan Furman wrote: > >> MyList is a list -- just a more specific kind of list -- as can be seen >> from its mro; this is analogous to a square (2 sets of parallel lines >> joined at 90 degree angles, both sets being the same length) also being >> a rectangle (2 sets of parallel lines joined at 90 degree angles). > > Possibly the worst analogy ever! *wink* > > http://en.wikipedia.org/wiki/Circle-ellipse_problem > > Also known as the square-rectangle problem. > > A better analogy might be, Lassie is a dog, and Flipper is a dolphin, so > they are different types of animal. But both dogs and dolphins are > mammals, so in that sense, Lassie and Flipper are both mammals and > therefore the same type of animal. It depends on what you mean by "type". I thought about using the mammal analogy instead, but geometry seemed simpler. *sigh* Oh, well, can't win 'em all! ~Ethan~