Path: csiph.com!newsfeed.hal-mli.net!feeder3.hal-mli.net!newsfeed.hal-mli.net!feeder1.hal-mli.net!newsfeed.xs4all.nl!newsfeed2a.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 0.004 X-Spam-Evidence: '*H*': 0.99; '*S*': 0.00; 'operator': 0.03; 'run- time': 0.05; 'referring': 0.07; 'machines.': 0.09; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'python': 0.11; 'finney': 0.16; 'implies': 0.16; 'objects.': 0.16; 'received:80.91.229.3': 0.16; 'received:plane.gmane.org': 0.16; 'header:User-Agent:1': 0.23; 'earlier': 0.24; 'references': 0.26; 'header:X-Complaints-To:1': 0.27; "doesn't": 0.30; 'subject:list': 0.30; 'object.': 0.31; 'obliged': 0.31; 'talked': 0.31; 'writes:': 0.31; 'problem': 0.35; 'beyond': 0.35; 'objects': 0.35; 'doubt': 0.36; 'received:com.au': 0.36; 'two': 0.37; 'problems': 0.38; 'ben': 0.38; 'to:addr:python-list': 0.38; 'to:addr:python.org': 0.39; 'received:org': 0.40; 'how': 0.40; 'skip:u 10': 0.60; 'tell': 0.60; 'provide': 0.64; 'talking': 0.65; 'received:125': 0.84; 'sufficient?': 0.84 X-Injected-Via-Gmane: http://gmane.org/ To: python-list@python.org From: Ben Finney Subject: Re: Explanation of list reference Date: Sat, 15 Feb 2014 17:19:38 +1100 References: <13208de8-0f85-4e60-b059-dc087c8fda41@googlegroups.com> <917ede6d-db7c-4a8c-8203-27677283776b@googlegroups.com> <871tz5piy0.fsf@elektro.pacujo.net> <87vbwho1i0.fsf@elektro.pacujo.net> <87mwhtnzdu.fsf@elektro.pacujo.net> <59c876d3-02f5-4f5a-8728-a5098472e03d@googlegroups.com> <6e96ba97-8ad0-4dad-9d11-b27bf9b237d0@googlegroups.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Gmane-NNTP-Posting-Host: vmx15867.hosting24.com.au X-Public-Key-ID: 0xBD41714B X-Public-Key-Fingerprint: 9CFE 12B0 791A 4267 887F 520C B7AC 2E51 BD41 714B X-Public-Key-URL: http://www.benfinney.id.au/contact/bfinney-gpg.asc X-Post-From: Ben Finney User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.4 (gnu/linux) Cancel-Lock: sha1:QKeyZg+1L1w+/mtgLhN9n8rLzf8= 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: 26 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1392445193 news.xs4all.nl 2950 [2001:888:2000:d::a6]:58867 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:66379 Rustom Mody writes: > Then you are obliged to provide some other way of understanding > object-identity How about: Every object has an identity, which is unique among all concurrently-existing objects. The ‘is’ operator queries whether two references are referring to objects with the same identity, which implies they are actually referring to the same object. Is that sufficient? > I earlier talked of the macro problems of identity, viz across > machines. Python doesn't make any promises about object identity beyond the current run-time of a single instance of a program. So while the problem you describe is interesting, it isn't relevant when talking about Python object identity. -- \ “When in doubt tell the truth. It will confound your enemies | `\ and astound your friends.” —Mark Twain, _Following the Equator_ | _o__) | Ben Finney