Path: csiph.com!usenet.pasdenom.info!weretis.net!feeder1.news.weretis.net!feeder.erje.net!newsfeed.xs4all.nl!newsfeed6.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 0.000 X-Spam-Evidence: '*H*': 1.00; '*S*': 0.00; 'argument': 0.04; 'none,': 0.05; 'arguments': 0.07; 'missed': 0.09; 'python': 0.09; 'happen.': 0.09; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'self.data': 0.09; 'typeerror:': 0.09; 'def': 0.10; 'passing': 0.15; '*class': 0.16; 'add(self,': 0.16; 'argument.': 0.16; 'discarded': 0.16; 'given)': 0.16; 'prog': 0.16; 'received:80.91.229.3': 0.16; 'received:plane.gmane.org': 0.16; 'wrote:': 0.17; 'pointed': 0.17; '>>>': 0.18; 'trying': 0.21; "i'd": 0.22; "i've": 0.23; 'header:In-Reply-To:1': 0.25; 'header :User-Agent:1': 0.26; '(most': 0.27; '???': 0.27; 'correct': 0.28; 'header:X-Complaints-To:1': 0.28; 'fine': 0.28; 'url:mailman': 0.29; 'skip:_ 10': 0.29; 'class': 0.29; 'classes': 0.30; 'error': 0.30; 'expect': 0.31; 'url:python': 0.32; 'file': 0.32; 'from:addr:yahoo.co.uk': 0.32; 'print': 0.32; 'url:listinfo': 0.32; "aren't": 0.33; 'traceback': 0.33; 'to:addr:python-list': 0.33; 'self': 0.34; 'wrong': 0.34; 'whatever': 0.35; 'returning': 0.35; 'received:org': 0.36; 'url:org': 0.36; 'anything': 0.36; 'should': 0.36; 'why': 0.37; 'passed': 0.37; 'data': 0.37; 'subject:: ': 0.38; 'mark': 0.38; 'nothing': 0.38; 'gives': 0.39; 'to:addr:python.org': 0.39; 'takes': 0.39; 'called': 0.39; 'header:Received:5': 0.40; 'url:mail': 0.40; 'first': 0.61; 'show': 0.63; 'gone': 0.64; 'here': 0.65; 'programme': 0.69; 'x):': 0.84 X-Injected-Via-Gmane: http://gmane.org/ To: python-list@python.org From: Mark Lawrence Subject: Re: classes Date: Wed, 24 Oct 2012 14:09:00 +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-78-146-0-43.as13285.net User-Agent: Mozilla/5.0 (Windows NT 6.0; rv:16.0) Gecko/20121010 Thunderbird/16.0.1 In-Reply-To: X-Antivirus: avast! (VPS 121024-0, 24/10/2012), 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: 91 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1351084020 news.xs4all.nl 6869 [2001:888:2000:d::a6]:59727 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:32037 On 24/10/2012 13:48, inshu chauhan wrote: > I was just trying out a programme for learning classes in python >>> >>> The prog below is showing an error which it should not show : >>> >>> class Bag: >>> def __init__(self, x): >>> self.data = [] >>> >> >> You do nothing with x here. Right so x shouldnot be in the argument. >> > Fine > > *class Bag: >> def __init__(self): >> self.data = []* >> >> >>> def add(self, x): >>> self.data.append(x) >>> def addtwice(self, x): >>> self.add(x) >>> self.add(x) No return given so it will default to returning None, but... >>> y = Bag(4) >>> >> >> Create y with an argument of 4 'which is discarded in the initialiser.' >> means ?? >> >> >> print " Adding twice of %4.2f gives " % (y.addtwice()) ...you seem to be expecting addtwice to be returning a Python float. Only you can tell us why as I've not yet gone to first year mind reading classes :) >>> >> >> There's no argument passed to addtwice here. ' why am I not passing y to >> addtwice here ?? You are passing y, it's called self. Why aren't you passing x? >> >> >> >>> >>> Error is : >>> >>> Traceback (most recent call last): >>> File "Z:\learning Python\learn5.py", line 35, in >>> print " Adding twice of %4.2f gives " % (y.addtwice()) >>> TypeError: addtwice() takes exactly 2 arguments (1 given) >>> >> >> Exactly what I'd expect to happen. What did you expect? I am learning >> .... >> >> >> >>> why the prog is having this error with self nd x as arguments ??? >>> >> >> What x argument? Clearly wrong as I've pointed out above. How can i >> correct it ?? Put whatever it is you want appended to self.data in the call to y.addtwice. And/or get addtwice to return the correct data type. And/or correct anything that I've missed like I did the first time around. >> >> >> -- >> Cheers. >> >> Mark Lawrence. >> >> -- >> http://mail.python.org/mailman/listinfo/python-list >> > -- Cheers. Mark Lawrence.