Path: csiph.com!fu-berlin.de!uni-berlin.de!not-for-mail From: Ian Kelly Newsgroups: comp.lang.python Subject: Re: Special attributes added to classes on creation Date: Sun, 3 Jul 2016 10:58:00 -0600 Lines: 26 Message-ID: References: <57793711$0$1611$c3e8da3$5496439d@news.astraweb.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-Trace: news.uni-berlin.de /8RqrUyAZsOGahRkidS4ogwVGdzqUdVktjGckyHfAQ7g== Return-Path: X-Original-To: python-list@python.org Delivered-To: python-list@mail.python.org X-Spam-Status: OK 0.039 X-Spam-Evidence: '*H*': 0.92; '*S*': 0.00; 'classes,': 0.05; 'newly': 0.09; "'__doc__',": 0.16; '2016': 0.16; 'metaclass': 0.16; 'received:io': 0.16; 'received:psf.io': 0.16; 'when?': 0.16; 'wrote:': 0.16; 'keys': 0.22; 'am,': 0.23; 'defined': 0.23; 'header:In-Reply-To:1': 0.24; 'handling': 0.27; 'message- id:@mail.gmail.com': 0.27; 'sequence': 0.27; "skip:' 10": 0.28; 'skip:q 20': 0.29; "i'm": 0.30; 'classes': 0.30; 'skip:[ 10': 0.31; 'point': 0.33; 'class': 0.33; 'url:python': 0.33; "d'aprano": 0.33; 'steven': 0.33; 'surprised': 0.33; 'that,': 0.34; 'received:google.com': 0.35; 'there': 0.36; 'url:org': 0.36; 'created': 0.36; 'to:addr:python-list': 0.36; 'subject:: ': 0.37; 'two': 0.37; 'to:addr:python.org': 0.40; 'url:3': 0.60; 'jul': 0.72; 'to:name:python': 0.84; 'url:datamodel': 0.84; 'subject:Special': 0.91; 'url:reference': 0.91 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to; bh=MHT1Fhv9NkG5IK44Tnk7VbID0/xtWvzPTYuIM+13HfE=; b=f569RLZa3sMOZfnOqMMR1wD3pTQ63+SvOf7W6IMJuEZaEAEvRNnac0dYr1EAVvxIqn 59EqMg08DZF70cufzCyG8PViYFBnwIf14KyRmgWNdD/Sw+O0wmpFmiq+Hsm/eDE9awi3 QsqB5DzrP0Jr4WHpfjLrK3tfRkz08+yedsLydqU/UeEd2xbhlV5e9KxHHywn6OVSVGyD C5VAoZjW4piMDrsh9XCCgdMkANlDQkimZsVkWisgP+BOxlyUTNV2O2crKN6GXdXxKlpB NpfOTyDlkKef3+IolvGKa9WHlLz35isLfbMjIULq2B5qJAhkDsYepOdHYUu5/qtvBztq 3NRQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to; bh=MHT1Fhv9NkG5IK44Tnk7VbID0/xtWvzPTYuIM+13HfE=; b=R4zsS9/tT5Q/EimTuUeMj84fqbo3I1cStoXayYb9a8m5u7L0+B9wPKDWORFUQXYj3m P4Niu4QtB6o5ERLpUJ8xy45S6pbNWKjrY1DRL6Yo4Ffd2VLWqKIbpIlTUVpFnkOEyGHn dy+rxqyOlB93EBUDXJKC/zw0ObWJs1drHeSPofgA4vTrGiBzZT86pEyCVQHEiKHIsUtb 9KpI0HarvnAxRj4O32gdjMs7VfWxiehTogldZOkcLaLKfImDE/tVBpETPeH0sTf2d3iF eyLrx/A0eazjl3p/oPCmw25ORbXZCfd8SyO1eJjhAW+P5RtDfpaFUPQxIi8YzlHKZ0FA 1Z0Q== X-Gm-Message-State: ALyK8tLTyEZEyqCqRp78QFBdOaV7a8K9MsOlI24fS2ZPQgEgJCjaab02MViHk6cLt352f0p3jBqamBV7gbFt0w== X-Received: by 10.202.225.212 with SMTP id y203mr4225205oig.47.1467565119705; Sun, 03 Jul 2016 09:58:39 -0700 (PDT) In-Reply-To: <57793711$0$1611$c3e8da3$5496439d@news.astraweb.com> X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.22 Precedence: list List-Id: General discussion list for the Python programming language List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Mailman-Original-Message-ID: X-Mailman-Original-References: <57793711$0$1611$c3e8da3$5496439d@news.astraweb.com> Xref: csiph.com comp.lang.python:111006 On Sun, Jul 3, 2016 at 10:02 AM, Steven D'Aprano wrote: > If I then try it against two identical (apart from their names) classes, I > get these results: > > > py> @process > ... class K: > ... x = 1 > ... > ['__dict__', '__doc__', '__module__', '__weakref__', 'x'] > py> class Q(metaclass=process): > ... x = 1 > ... > ['__module__', '__qualname__', 'x'] > Now if I check the newly created Q, I see the same keys K has: > > py> sorted(Q.__dict__.keys()) > ['__dict__', '__doc__', '__module__', '__weakref__', 'x'] > > > Is there any documentation for exactly what keys are added to classes when? I'm only aware of the sequence defined at https://docs.python.org/3/reference/datamodel.html#customizing-class-creation. Based on that, I'm surprised to even see __module__ and __qualname__ in there at the point when the metaclass is handling it.