Path: csiph.com!usenet.pasdenom.info!news.albasani.net!feeder.erje.net!eu.feeder.erje.net!newsfeed.xs4all.nl!newsfeed3.news.xs4all.nl!xs4all!newsgate.cistron.nl!newsgate.news.xs4all.nl!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 0.010 X-Spam-Evidence: '*H*': 0.98; '*S*': 0.00; 'from:addr:yahoo.co.uk': 0.04; 'lawrence': 0.09; 'pointers': 0.09; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'thus,': 0.09; 'language.': 0.14; 'crop': 0.16; 'namespace.': 0.16; 'patches': 0.16; 'received:80.91.229.3': 0.16; 'received:plane.gmane.org': 0.16; 'essential': 0.16; 'index': 0.16; 'language': 0.16; 'wrote:': 0.18; 'discussion': 0.18; 'bit': 0.19; 'code,': 0.22; 'header:User-Agent:1': 0.23; '---': 0.24; 'second': 0.26; 'defined': 0.27; 'header:X -Complaints-To:1': 0.27; 'header:In-Reply-To:1': 0.27; "doesn't": 0.30; 'subject:list': 0.30; "i'm": 0.30; 'concern': 0.31; 'piece': 0.31; 'url:python': 0.33; 'could': 0.34; 'but': 0.35; 'there': 0.35; 'entry': 0.36; 'url:org': 0.36; 'url:library': 0.38; 'to:addr:python-list': 0.38; 'explain': 0.39; '(from': 0.39; 'to:addr:python.org': 0.39; 'received:org': 0.40; 'skip:u 10': 0.60; 'middle': 0.60; 'free': 0.61; 'mentioned': 0.61; 'url:3': 0.61; 'viruses': 0.61; 'information': 0.63; 'protection': 0.63; 'such': 0.63; 'our': 0.64; 'antivirus': 0.68; 'presented': 0.69; 'carefully': 0.74; 'sole': 0.78; 'worms': 0.84 X-Injected-Via-Gmane: http://gmane.org/ To: python-list@python.org From: Mark Lawrence Subject: Re: Explanation of list reference Date: Sun, 16 Feb 2014 18:36:44 +0000 References: <13208de8-0f85-4e60-b059-dc087c8fda41@googlegroups.com> <59c876d3-02f5-4f5a-8728-a5098472e03d@googlegroups.com> <6e96ba97-8ad0-4dad-9d11-b27bf9b237d0@googlegroups.com> <878utcmqwo.fsf@elektro.pacujo.net> <8ca61d1a-b4f6-4677-9cd6-ba15c251f173@googlegroups.com> <87eh33gcmt.fsf@elektro.pacujo.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Gmane-NNTP-Posting-Host: host-78-147-189-196.as13285.net User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:24.0) Gecko/20100101 Thunderbird/24.3.0 In-Reply-To: <87eh33gcmt.fsf@elektro.pacujo.net> X-Antivirus: avast! (VPS 140216-0, 16/02/2014), Outbound message X-Antivirus-Status: Clean X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.15 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: 49 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1392575819 news.xs4all.nl 2867 [2001:888:2000:d::a6]:37927 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:66561 On 16/02/2014 18:01, Marko Rauhamaa wrote: > Rustom Mody : > >> But for that Ive to use is >> And as a teacher Ive to explain is >> Might as well use C and get on with pointers >> >> To me 'is' is a can of worms > > I'm not against "is," but it must be carefully defined and taught. > > As far as "x is None" is concerned, a key piece of information is > presented on : > > None > The sole value of the type NoneType. > > Unfortunately the page is a bit confusing. It says: > > A small number of constants live in the built-in namespace. > > So an essential characteristic of the None object (uniqueness) is > mentioned in the middle of the discussion on the built-in namespace. The > index doesn't contain an entry on NoneType. > > Thus, there might still be a nagging concern that a second NoneType > object x such that > > x == None and x is not None > > could crop up (from native code, perhaps). > > > Marko > Patches are always welcome :) -- My fellow Pythonistas, ask not what our language can do for you, ask what you can do for our language. Mark Lawrence --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com