Path: csiph.com!usenet.pasdenom.info!weretis.net!feeder1.news.weretis.net!feeder.erje.net!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 0.026 X-Spam-Evidence: '*H*': 0.95; '*S*': 0.00; '16,': 0.03; 'raises': 0.07; 'so?': 0.07; 'type,': 0.07; 'python': 0.09; 'wraps': 0.09; 'aug': 0.13; 'belongs': 0.16; 'though)': 0.16; 'wrote:': 0.17; 'thu,': 0.17; '(or': 0.18; 'together.': 0.21; '(on': 0.22; 'subject:skip:i 10': 0.22; 'header:In-Reply-To:1': 0.25; 'header :User-Agent:1': 0.26; 'question': 0.27; '(as': 0.27; 'correct': 0.28; 'actual': 0.28; 'steven': 0.29; 'class': 0.29; 'returned': 0.30; 'function': 0.30; 'stuff': 0.30; 'could': 0.32; '+0200,': 0.33; 'function.': 0.33; 'to:addr:python-list': 0.33; '(with': 0.33; 'another': 0.33; 'so,': 0.35; 'but': 0.36; "wasn't": 0.36; 'method': 0.36; 'should': 0.36; 'charset:us-ascii': 0.36; 'bad': 0.37; 'ok,': 0.37; 'why': 0.37; 'far': 0.37; 'subject:: ': 0.38; 'object': 0.38; 'received:10': 0.38; 'to:addr:python.org': 0.39; 'think': 0.40; 'content-disposition:inline': 0.60; 'first': 0.61; 'thomas': 0.62; 'more': 0.63; 'realized': 0.71; 'saw': 0.75; '"what': 0.84; 'buzz': 0.84; 'received:10.94': 0.84; 'tie': 0.84; '"how': 0.91 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=uni-mainz.de; i=@uni-mainz.de; q=dns/txt; s=ironport; t=1345136055; x=1376672055; h=date:from:to:subject:message-id:references:mime-version: in-reply-to; bh=MZ0GOQp/Q7CjjILx/OeIlLAUdTmiIYR9B0kgi22TxMI=; b=i9yho6GW2GUXdq7EY5PryyskgmMkIAH/jXAioGm++F76xabfUqKlK5AC 9n3KIYS+VPbd9248ERzfMqulB7eYTVARgpr5o6WjHy5ecHmQaw3wIGM5x CWSpm5AF14UfLoNFqspS4aUXbxQXv2dNMDRL42+/KBByK6Wvh2ut1Cfl5 s=; X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: Ap4EAN4kLVAKXgZY/2dsb2JhbABFtwGEM4IgAQEFOk8IAxgeEBQoIYgkumqLCoM7gjxgA5VOkBOCYQ Date: Thu, 16 Aug 2012 18:54:12 +0200 From: Thomas Bach To: Subject: Re: Dynamically determine base classes on instantiation References: <502c3bc2$0$29978$c3e8da3$5496439d@news.astraweb.com> <502d0d74$0$6986$e4fe514c@news2.news.xs4all.nl> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <502d0d74$0$6986$e4fe514c@news2.news.xs4all.nl> User-Agent: Mutt/1.5.21 (2010-09-15) X-Originating-IP: [92.225.137.41] 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: 29 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1345136056 news.xs4all.nl 6851 [2001:888:2000:d::a6]:51992 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:27181 On Thu, Aug 16, 2012 at 05:10:43PM +0200, Hans Mulder wrote: > On 16/08/12 14:52:30, Thomas Bach wrote: > > > > So, my question (as far as I can see it, please correct me if I am > > wrong) is less of the "How do I achieve this?"-kind, but more of the > > "What is a clean design for this?"-kind. My intuitive thought was that > > the `merge' function should be a part of the object returned from `F'. > > The misunderstanding is that you feel F should return an object with > a 'merge' method and a varying abse type, while Steven and others > think that F should be a function. OK, then my design wasn't so bad in the first place. :) I made a class `Model' which wraps the actual type and realized `merge' and `F' (with a better name, though) as classmethods of `Model' in order to tie together the stuff that belongs together. By the way, another need I saw for this design was that setattr(Model(), 'foo', {'bar': int}) works, whereas setattr(dict(), 'foo', {'bar': int}) raises an AttributeError (on Python 3.2). Could someone give me the buzz word (or even an explanation) on why that is so? Thomas Bach