Path: csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!weretis.net!feeder4.news.weretis.net!newsreader4.netcologne.de!news.netcologne.de!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 0.002 X-Spam-Evidence: '*H*': 1.00; '*S*': 0.00; 'attributes': 0.05; 'instance,': 0.05; 'attribute': 0.07; 'lately': 0.07; 'tends': 0.07; "everyone's": 0.09; 'mutable': 0.09; 'necessary,': 0.09; 'am,': 0.12; 'def': 0.13; 'argument': 0.15; '@property': 0.16; 'arbitrarily': 0.16; 'methods,': 0.16; 'opposed,': 0.16; 'versus': 0.16; 'cc:addr:python-list': 0.16; 'wed,': 0.17; 'wrote:': 0.18; 'instance': 0.18; 'cc:no real name:2**0': 0.20; 'cheers,': 0.20; 'dec': 0.22; "doesn't": 0.22; 'header:In-Reply-To:1': 0.22; 'figure': 0.23; 'breaks': 0.23; 'complain': 0.23; "python's": 0.24; 'classes': 0.26; 'code.': 0.26; 'all,': 0.28; 'cc:addr:gmail.com': 0.28; 'cc:addr:python.org': 0.29; 'second': 0.29; 'kelly': 0.30; 'useless': 0.30; "i've": 0.31; 'dependent': 0.32; 'wondering': 0.32; "can't": 0.32; 'header:User-Agent:1': 0.33; 'decide': 0.33; 'something': 0.35; 'switch': 0.35; 'properties': 0.36; 'cc:2**1': 0.36; 'drives': 0.37; 'variables': 0.37; "there's": 0.37; 'doing': 0.38; 'using': 0.38; 'plain': 0.39; 'more': 0.61; '2011': 0.61; 'property': 0.63; 'direct': 0.67; 'received:62': 0.70; '.net,': 0.84; 'low,': 0.84; 'nuts': 0.84; 'subject:Property': 0.84; 'value):': 0.84; 'subject:Abuse': 0.91 X-IronPort-AV: E=Sophos;i="4.71,353,1320620400"; d="scan'208";a="41990" X-Virus-Scanned: amavisd-new at zimbra.sequans.com Date: Wed, 14 Dec 2011 17:37:15 +0100 From: Jean-Michel Pichavant User-Agent: Mozilla-Thunderbird 2.0.0.24 (X11/20100328) MIME-Version: 1.0 To: Ian Kelly Subject: Re: Property Abuse References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: python-list@python.org, Felipe O 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: 41 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1323880638 news.xs4all.nl 6866 [2001:888:2000:d::a6]:56452 X-Complaints-To: abuse@xs4all.nl Xref: x330-a1.tempe.blueboxinc.net comp.lang.python:17223 Ian Kelly wrote: > On Wed, Dec 14, 2011 at 1:28 AM, Felipe O wrote: > >> Hi All, >> I was wondering what everyone's thought process was regarding properties. >> Lately I find I've been binging on them and have classes with > 10 >> properties. While pylint doesn't complain (yet), it tends to be picky about >> keeping instance attribute counts low, so I figure there's something against >> that. How do you guys decide between using properties versus getter methods, >> or how do you refactor them if neither? >> > > I prefer direct instance attribute access where possible*, properties > where necessary, and methods where an argument is needed or the > relationship is more complex than get/set/delete. > > * One of the strengths of Python's property system** is that you can > switch between plain attributes and mutable properties as needed > without breaking dependent code. Often I see people doing this, which > drives me nuts with its useless verbosity, when a plain instance > attribute would have sufficed: > > @property > def foo(self): > return self._foo > > @foo.setter > def foo(self, value): > self._foo = value > > ** As opposed, for instance, to the .NET property system. You can't > arbitrarily switch between public member variables and public > properties in .NET, because it breaks ABI. > > Cheers, > Ian > I second this opinion, plain attributes are what's required most of the time. JM