Path: csiph.com!usenet.pasdenom.info!gegeweb.org!usenet-fr.net!nerim.net!novso.com!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 0.000 X-Spam-Evidence: '*H*': 1.00; '*S*': 0.00; 'python.': 0.02; '(except': 0.07; 'initialize': 0.07; '__init__': 0.09; 'from:addr:ethan': 0.09; 'from:addr:stoneleaf.us': 0.09; 'from:name:ethan furman': 0.09; 'message-id:@stoneleaf.us': 0.09; 'method,': 0.09; '~ethan~': 0.09; 'python': 0.11; '[1].': 0.16; '__new__': 0.16; 'behavior,': 0.16; 'cls': 0.16; 'enum': 0.16; 'it),': 0.16; 'kitchen': 0.16; 'old-style': 0.16; 'recipes': 0.16; 'stuff.': 0.16; 'two,': 0.16; 'sat,': 0.16; 'wrote:': 0.18; '(where': 0.19; 'foundation,': 0.20; 'feb': 0.22; 'header:User-Agent:1': 0.23; '(or': 0.24; 'header:In-Reply-To:1': 0.27; 'chris': 0.29; '[1]': 0.29; 'along': 0.30; "d'aprano": 0.31; 'steven': 0.31; 'quite': 0.32; 'skip:_ 10': 0.34; 'subject:the': 0.34; 'could': 0.34; 'basic': 0.35; 'classes': 0.35; 'there': 0.35; 'done': 0.36; 'charset:us-ascii': 0.36; 'two': 0.37; 'easily': 0.37; 'being': 0.38; 'skip:o 20': 0.38; 'to:addr:python-list': 0.38; 'pm,': 0.38; 'anything': 0.39; 'to:addr:python.org': 0.39; 'called': 0.40; 'how': 0.40; 'received:173': 0.61; 'further': 0.61; 'useful.': 0.68; 'behavior': 0.77 Date: Sat, 01 Feb 2014 00:28:03 -0800 From: Ethan Furman User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:16.0) Gecko/20121010 Thunderbird/16.0.1 MIME-Version: 1.0 To: python-list@python.org Subject: Re: __init__ is the initialiser References: <52ec6d1f$0$29972$c3e8da3$5496439d@news.astraweb.com> <52ec8b51$0$29972$c3e8da3$5496439d@news.astraweb.com> In-Reply-To: <52ec8b51$0$29972$c3e8da3$5496439d@news.astraweb.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - gator3304.hostgator.com X-AntiAbuse: Original Domain - python.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - stoneleaf.us X-BWhitelist: no X-Source-IP: 173.12.184.233 X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: ([173.12.184.233]) [173.12.184.233]:37457 X-Source-Auth: ethan+stoneleaf.us X-Email-Count: 1 X-Source-Cap: dG9idWs7dG9idWs7Z2F0b3IzMzA0Lmhvc3RnYXRvci5jb20= 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: 19 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1391244676 news.xs4all.nl 2937 [2001:888:2000:d::a6]:46862 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:65205 On 01/31/2014 09:51 PM, Steven D'Aprano wrote: > On Sat, 01 Feb 2014 15:35:17 +1100, Chris Angelico wrote: >> >> The two methods could have been done as a single method, __construct__, >> in which you get passed a cls instead of a self, and you call >> self=super().__construct__() and then initialize stuff. > > That would be called __new__ in Python. There's no *need* to use __init__ > for anything (except old-style classic classes in Python 2). While there may not be a /need/ for two, having two is quite handy. Having __new__ take care of the nuts and bolts (or foundation, as Terry put it), and being able to further customize with __init__ (where the kitchen goes, how many bedrooms, to follow along with Terry) is quite useful. One of my favorite Enum recipes uses that pattern to have some basic behavior, with some other behavior that is easily overridable/extendable [1]. -- ~Ethan~ [1] http://stackoverflow.com/q/19330460/208880