Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!feeder.erje.net!eu.feeder.erje.net!newsfeed.xs4all.nl!newsfeed2a.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 0.024 X-Spam-Evidence: '*H*': 0.95; '*S*': 0.00; 'class,': 0.07; 'referring': 0.07; 'dan': 0.09; 'decorator': 0.09; 'instance.': 0.09; 'methods,': 0.09; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'subject:method': 0.09; 'argument.': 0.16; 'finney': 0.16; 'merely': 0.16; 'received:80.91.229.3': 0.16; 'received:plane.gmane.org': 0.16; 'subject:class': 0.16; 'trying': 0.19; 'later': 0.20; 'seems': 0.21; 'example': 0.22; 'header:User- Agent:1': 0.23; 'specify': 0.24; 'class.': 0.26; 'header:X -Complaints-To:1': 0.27; 'function': 0.29; 'specifically': 0.29; 'feature': 0.29; "doesn't": 0.30; 'apparently': 0.31; 'way?': 0.31; 'writes:': 0.31; 'class': 0.32; '(i.e.': 0.33; 'actual': 0.34; 'subject:with': 0.35; "can't": 0.35; 'there': 0.35; 'subject:one': 0.36; 'done': 0.36; 'method': 0.36; 'useful': 0.36; 'subject:?': 0.36; 'should': 0.36; 'expected': 0.38; 'ben': 0.38; 'to:addr:python-list': 0.38; 'rather': 0.38; 'to:addr:python.org': 0.39; 'received:org': 0.40; 'office': 0.60; 'simple,': 0.60; "you're": 0.61; 'first': 0.61; 'complete': 0.62; 'show': 0.63; 'such': 0.63; 'refer': 0.63; 'more': 0.64; 'hours': 0.66; 'between': 0.67; 'importantly,': 0.68; 'a.m.': 0.84; 'athens': 0.84; 'clearer': 0.84; 'improvement': 0.84; 'received:125': 0.84; 'whereas': 0.91; 'why?': 0.91 X-Injected-Via-Gmane: http://gmane.org/ To: python-list@python.org From: Ben Finney Subject: Re: Decorating one method of a class C with another method of class C? Date: Sat, 07 Jun 2014 10:28:03 +1000 References: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Gmane-NNTP-Posting-Host: jigong.madmonks.org X-Public-Key-ID: 0xAC128405 X-Public-Key-Fingerprint: 517C F14B B2F3 98B0 CB35 4855 B8B2 4C06 AC12 8405 X-Public-Key-URL: http://www.benfinney.id.au/contact/bfinney-pubkey.asc X-Post-From: Ben Finney User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.4 (gnu/linux) Cancel-Lock: sha1:1wjT/1lxX6KXLrBOiDdmbx88bp4= 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: 35 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1402100900 news.xs4all.nl 2887 [2001:888:2000:d::a6]:34068 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:72891 Dan Stromberg writes: > Is there a way of decorating method1 of class C using method2 of class > C? Can you give a concrete example (i.e. not merely hypothetical) where this would be a useful feature (i.e. an actual improvement over the absence of the feature), and why? > It seems like there's a chicken-and-the-egg problem; the class doesn't > seem to know what "self" is until later in execution so there's > apparently no way to specify @self.method2 when def'ing method1. You're referring specifically to instance methods, it seems. Right, there's no instance *of* the class during the *definition* of the class, so ‘self’ can't refer to such an instance. Also, an instance method needs to get the instance as the first parameter, whereas the decorator must accept the to-be-decorated function as its argument. So I don't see what you're trying to achieve, rather than the more straightforward and clearer use of a decorator function which *isn't* a method in the same class. Can you show a Simple, Self-Contained Complete Example to show us what you're trying to do? More importantly, why you think it should be done this way? -- \ “Visitors are expected to complain at the office between the | `\ hours of 9 and 11 a.m. daily.” —hotel, Athens | _o__) | Ben Finney