Path: csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!news.albasani.net!feeder.news-service.com!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; 'else:': 0.03; 'attributes': 0.05; 'hettinger': 0.07; 'names.': 0.07; 'attribute': 0.09; 'attribute.': 0.09; 'attributes,': 0.09; 'override': 0.09; 'underlying': 0.09; 'pm,': 0.11; 'def': 0.13; 'wrote:': 0.14; '@property': 0.16; 'aliases': 0.16; 'attributes.': 0.16; 'finney': 0.16; 'methods,': 0.16; 'received:192.168.200': 0.16; 'class,': 0.16; 'wrap': 0.19; 'header:In-Reply-To:1': 0.22; 'raymond': 0.22; 'skip:_ 20': 0.24; 'define': 0.26; 'pass': 0.27; 'class': 0.29; 'fine.': 0.29; 'all,': 0.31; 'to:addr:python-list': 0.32; 'idea': 0.32; 'received:192': 0.34; 'header:User-Agent:1': 0.35; 'received:192.168': 0.37; 'it?': 0.37; 'skip:o 20': 0.37; 'refer': 0.37; 'but': 0.38; 'current': 0.38; 'set': 0.39; 'to:addr:python.org': 0.39; 'could': 0.39; 'how': 0.39; 'charset:windows-1252': 0.61; 'mar': 0.64; '\x93the': 0.91 X-IronPort-AV: E=Sophos;i="4.63,281,1299452400"; d="scan'208";a="1174383" X-Virus-Scanned: amavisd-new at zimbra.sequans.com Date: Fri, 01 Apr 2011 11:54:06 +0200 From: Jean-Michel Pichavant User-Agent: Mozilla-Thunderbird 2.0.0.24 (X11/20100328) MIME-Version: 1.0 To: python-list@python.org Subject: Re: Alias for an attribute defined in a superclass References: <87sju3ndjo.fsf@benfinney.id.au> <787d36b9-e31d-4b61-a14e-770337cfc280@a11g2000pro.googlegroups.com> In-Reply-To: <787d36b9-e31d-4b61-a14e-770337cfc280@a11g2000pro.googlegroups.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 8bit 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: 64 NNTP-Posting-Host: 82.94.164.166 X-Trace: 1301651655 news.xs4all.nl 41110 [::ffff:82.94.164.166]:51509 X-Complaints-To: abuse@xs4all.nl Xref: x330-a1.tempe.blueboxinc.net comp.lang.python:2342 Raymond Hettinger wrote: > On Mar 31, 3:14 pm, Ben Finney wrote: > >> Howdy all, >> >> I want to inherit from a class, and define aliases for many of its >> attributes. How can I refer to “the attribute that will be available by >> name ‘spam’ once this class is defined”? >> >> class Foo(object): >> def spam(self): >> pass >> >> def eggs(self): >> pass >> >> class Bar(Foo): >> beans = Foo.spam >> mash = Foo.eggs >> >> Is that the right way to do it? >> > > For methods, that will work just fine. For attributes, you will need > to make @property accessors that get and set the underlying attribute. > > > Raymond > For attributes you could also override __getattribute__ & __setattr__ to wrap Bar's names into Foo's names. Could work also for methods, but for methods your current idea is much more simple. class Foo(object): def __init__(self): self.spam = 'someSpam' self.eggs = 'fewEggs' def vanilla(self): return self.spam class Bar(Foo): _map = { 'beans': 'spam', 'mash': 'eggs', 'chocolate': 'vanilla', } def __getattribute__(self, attribute): getSafely = object.__getattribute__ _map = getSafely(self, '_map') if attribute in _map: return getSafely(self, _map[attribute]) else: return getSafely(self, attribute) Bar().chocolate() 'someSpam' Bar().mash 'fewEggs' JM