Path: csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!aioe.org!news.stack.nl!newsfeed.xs4all.nl!newsfeed5.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 0.006 X-Spam-Evidence: '*H*': 0.99; '*S*': 0.00; 'c++,': 0.07; 'python': 0.08; 'wrong,': 0.09; 'def': 0.13; 'argument': 0.15; 'class,': 0.15; '__init__': 0.16; 'dictionary,': 0.16; 'needless': 0.16; 'subject:instance': 0.16; 'url:effbot': 0.16; 'url:zone': 0.16; 'variable.': 0.16; 'cc:addr:python-list': 0.16; 'syntax': 0.16; 'this:': 0.16; '(i.e.': 0.17; 'wrote:': 0.18; 'instance': 0.18; 'working.': 0.18; 'say,': 0.19; '(which': 0.19; 'cheers,': 0.20; 'cc:no real name:2**0': 0.21; "doesn't": 0.22; 'header:In-Reply- To:1': 0.22; 'feb': 0.22; 'assigning': 0.23; 'dictionary': 0.23; 'fine,': 0.23; 'received:209.85.220': 0.25; 'cc:2**0': 0.26; 'work.': 0.27; 'function': 0.27; 'effect': 0.28; 'message- id:@mail.gmail.com': 0.29; 'class': 0.29; 'cc:addr:python.org': 0.29; 'pm,': 0.29; '(and': 0.30; 'object.': 0.30; 'sun,': 0.30; 'chris': 0.30; 'creates': 0.31; 'subject:?': 0.31; 'rather': 0.34; 'assignment': 0.34; 'function.': 0.34; 'something': 0.35; 'subject:How': 0.35; 'subject:can': 0.35; 'everyone.': 0.37; 'created': 0.37; 'but': 0.37; 'received:google.com': 0.37; 'skip:_ 10': 0.38; 'received:209.85': 0.38; 'uses': 0.38; 'could': 0.38; 'doing': 0.38; 'getting': 0.38; 'url:org': 0.39; 'received:209': 0.39; 'being': 0.40; 'john': 0.61; 'header:Received:6': 0.61; 'custom': 0.61; 'believe': 0.65; 'subject:like': 0.67; 'url:htm': 0.69; '26,': 0.73; 'subject:make': 0.73; '11:24': 0.84; 'sender:addr:chris': 0.84; 'url:rebertia': 0.84 Received-SPF: pass (google.com: domain of chris@rebertia.com designates 10.52.67.229 as permitted sender) client-ip=10.52.67.229; Authentication-Results: mr.google.com; spf=pass (google.com: domain of chris@rebertia.com designates 10.52.67.229 as permitted sender) smtp.mail=chris@rebertia.com; dkim=pass header.i=chris@rebertia.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rebertia.com; s=google; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type :content-transfer-encoding; bh=Ln5HGN1+bt7o+lYcyQObdVnWv9QOSA2k7wFOaQ//Jj4=; b=AQGK2sFcmmroC30GNwwhl8XLDK2XydRSFYcIKYQW4kakW51ilx9FJcYAjrr/ah/AKd p5dNKRnG1J4YXdaboTJhzMGlI2nnLoW3v2MkrW1fWsibPnq7noNB45mR1mu+7oxPWonq 0ChRn8qeGSmnS3PDH/NMBVShb4ety/tJRaBcY= MIME-Version: 1.0 Sender: chris@rebertia.com In-Reply-To: References: Date: Sun, 26 Feb 2012 23:39:01 -0800 X-Google-Sender-Auth: fio2ENw0dACQt29Rhf4zXoDyUxM Subject: Re: How can I make an instance of a class act like a dictionary? From: Chris Rebert To: John Salerno Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Gm-Message-State: ALoCoQkqBegAgPagfZ5xtuujNuPyKxvSxDKAh7fzez6l1rmD5EDO4lannNFxgNY5nzTzuJYYHyW4 Cc: python-list@python.org 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: 32 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1330328350 news.xs4all.nl 6870 [2001:888:2000:d::a6]:37108 X-Complaints-To: abuse@xs4all.nl Xref: x330-a1.tempe.blueboxinc.net comp.lang.python:20926 On Sun, Feb 26, 2012 at 11:24 PM, John Salerno wrote: > Hi everyone. I created a custom class and had it inherit from the > "dict" class, and then I have an __init__ method like this: > > def __init__(self): > =C2=A0 =C2=A0 =C2=A0 =C2=A0self =3D create() > > The create function creates and returns a dictionary object. Needless > to say, this is not working. When I create an instance of the above > class, it is simply an empty dictionary rather than the populated > dictionary being created by the create function. Am I doing the > inheritance wrong, or am I getting the above syntax wrong by assigning > the return value to self? Assignment to `self` has no effect outside the method in question; Python uses call-by-object (http://effbot.org/zone/call-by-object.htm ) for argument passing. Even in something like C++, I believe assignment to `this` doesn't work. > I know I could do self.variable =3D create() and that works fine, but I > thought it would be better (and cleaner) simply to use the instance > itself as the dictionary, rather than have to go through an instance > variable. Call the superclass (i.e. dict's) initializer (which you ought to be doing anyway): super(YourClass, self).__init__(create()) Cheers, Chris -- http://rebertia.com