Path: csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!gegeweb.org!de-l.enfer-du-nord.net!feeder1.enfer-du-nord.net!feeder.news-service.com!newsfeed.xs4all.nl!newsfeed6.news.xs4all.nl!xs4all!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; 'python.': 0.04; 'attributes': 0.05; 'cpython': 0.05; 'attribute': 0.07; 'received:verizon.net': 0.07; 'terry': 0.07; 'python': 0.08; '*is*': 0.09; 'builtin': 0.09; 'determines': 0.09; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:80.91.229.12': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'received:lo.gmane.org': 0.09; 'classes,': 0.13; '6:52': 0.16; 'assignable': 0.16; 'assignment.': 0.16; 'attribute,': 0.16; 'attributes.': 0.16; 'instances.': 0.16; 'reedy': 0.16; '{}"': 0.16; 'wrote:': 0.16; 'advance': 0.18; 'jan': 0.19; 'so.': 0.22; 'assume': 0.22; 'header:In-Reply-To:1': 0.22; 'restrict': 0.23; 'pm,': 0.24; "i'm": 0.27; 'classes': 0.28; 'true,': 0.29; 'also.': 0.30; 'class': 0.30; 'to:addr:python- list': 0.33; '...': 0.34; 'header:User-Agent:1': 0.34; 'but,': 0.34; 'be,': 0.34; 'safely': 0.34; 'sense,': 0.34; 'header:X -Complaints-To:1': 0.35; 'beginning': 0.36; 'none': 0.37; 'are.': 0.37; 'but': 0.37; 'something': 0.37; 'could': 0.38; 'received:org': 0.38; 'some': 0.38; 'should': 0.38; 'subject:: ': 0.39; 'header:Mime-Version:1': 0.39; 'user': 0.39; 'to:addr:python.org': 0.39; 'subject': 0.61; 'believe': 0.65; 'details': 0.65; 'violation': 0.67; 'candide': 0.84; 'subject:types': 0.84 X-Injected-Via-Gmane: http://gmane.org/ To: python-list@python.org From: Terry Reedy Subject: Re: __dict__ attribute for built-in types Date: Thu, 27 Oct 2011 22:44:26 -0400 References: <4ea92dae$0$20639$426a74cc@news.free.fr> <4ea96437$0$24971$426a74cc@news.free.fr> <4ea9d8e6$0$29968$c3e8da3$5496439d@news.astraweb.com> <4ea9e0ba$0$2261$426a74cc@news.free.fr> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Gmane-NNTP-Posting-Host: pool-74-109-121-73.phlapa.fios.verizon.net User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:6.0) Gecko/20110812 Thunderbird/6.0 In-Reply-To: <4ea9e0ba$0$2261$426a74cc@news.free.fr> 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: 1319769884 news.xs4all.nl 6863 [2001:888:2000:d::a6]:47820 X-Complaints-To: abuse@xs4all.nl Xref: x330-a1.tempe.blueboxinc.net comp.lang.python:15075 On 10/27/2011 6:52 PM, candide wrote: > No but I'm expecting from Python documentation to mention the laws of > Python ... The details of CPython builtin classes are not laws of Python. It *is* a 'law of Python' that classes can use 'slots = ' to restrict the attributes of instances. By implication, builtin classes in any implementation do not have to allow attribute assignment. I do not believe it would be a violation if some implementation did so. None of this is to say that we could not say something on the subject at the beginning of the 'built-in types' chapter of the lib manual. > OK but I'm talking about classes, not instances : Yes you are. The class determines whether its instances have assignable new attributes. > 42 has no __dict__ > attribute but, > may be, 43 _has_ such attribute, who knows in advance ? ;) True, in a sense, but if the class allowed a user to execute "42.__dict__ = {}" then you could safely assume that "43.xxx = z" should work also. -- Terry Jan Reedy