Path: csiph.com!usenet.pasdenom.info!news.albasani.net!newsfeed.freenet.ag!news2.euro.net!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 0.000 X-Spam-Evidence: '*H*': 1.00; '*S*': 0.00; 'none,': 0.05; 'dynamically': 0.07; 'none)': 0.07; 'statically': 0.07; 'subject:code': 0.07; 'python': 0.09; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'variables,': 0.09; 'gui': 0.11; 'language,': 0.11; 'message-id:@dough.gmane.org': 0.16; 'overwriting': 0.16; 'received:80.91.229.3': 0.16; 'received:plane.gmane.org': 0.16; 'which,': 0.16; 'wrote:': 0.17; 'variables': 0.17; '(not': 0.20; 'variable': 0.20; 'names.': 0.22; 'example': 0.23; 'programming': 0.23; 'header:In-Reply-To:1': 0.25; 'header:User-Agent:1': 0.26; 'possibly': 0.27; 'question': 0.27; 'andrew': 0.27; "doesn't": 0.28; 'header:X-Complaints-To:1': 0.28; 'subsequently': 0.29; "i'm": 0.29; 'standards': 0.30; 'code': 0.31; 'from:addr:yahoo.co.uk': 0.32; 'print': 0.32; 'to:addr:python-list': 0.33; 'code:': 0.33; 'changed': 0.34; 'thanks': 0.34; 'subject:?': 0.35; 'received:org': 0.36; 'totally': 0.36; 'subject:with': 0.36; 'subject:: ': 0.38; 'mark': 0.38; 'to:addr:python.org': 0.39; 'header:Received:5': 0.40; 'your': 0.60; 'as:': 0.75; 'subject:this': 0.84; 'flame': 0.84; 'reveal': 0.84; 'received:89': 0.86 X-Injected-Via-Gmane: http://gmane.org/ To: python-list@python.org From: Mark Lawrence Subject: Re: What's wrong with this code? Date: Tue, 24 Jul 2012 07:23:37 +0100 References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Gmane-NNTP-Posting-Host: host-89-243-205-160.as13285.net User-Agent: Mozilla/5.0 (Windows NT 6.0; rv:14.0) Gecko/20120713 Thunderbird/14.0 In-Reply-To: X-Antivirus: avast! (VPS 120723-2, 23/07/2012), Outbound message X-Antivirus-Status: Clean 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: 67 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1343110960 news.xs4all.nl 6912 [2001:888:2000:d::a6]:57268 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:25956 On 24/07/2012 02:19, Andrew Cooper wrote: > On 23/07/2012 15:50, Stone Li wrote: >> I'm totally confused by this code: >> >> Code: >> >> a = None >> b = None >> c = None >> d = None >> x = [[a,b], >> [c,d]] >> e,f = x[1] >> print e,f >> c = 1 >> d = 2 >> print e,f >> e = 1 >> f = 2 >> print c,d >> >> Output: >> >> None None >> None None >> 1 2 >> >> >> >> I'm expecting the code as: >> >> None None >> 1 2 >> 1 2 >> >> >> >> What's wrong? >> And this question made my GUI program totally out of control. >> Thanks > > c = 1 and d = 2 are overwriting the variable c (= None) and d (= None) > with new variables 1 and 2. As x already captured c and d while they > were none, the variables e and f do not change (not would the, even if > you subsequently changed x) > > Python is a statically scoped language, whereas the functionality you > are expecting would be an example of dynamically scoped. > > Care to reveal your programming background? > > ~Andrew > strictly speaking Python doesn't have variables, it has names. This will possibly start a flame war which, by the standards of this ng/ml, will be an intense conflagration, hence the duck and cover. -- Cheers. Mark Lawrence.