Path: csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!aioe.org!feeder.news-service.com!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 0.034 X-Spam-Evidence: '*H*': 0.93; '*S*': 0.00; 'subject:Python': 0.04; '(python': 0.05; 'disagree': 0.07; 'variable,': 0.07; 'slightly': 0.12; 'am,': 0.14; 'wrote:': 0.14; 'finney': 0.16; 'nowhere.': 0.16; 'pointer,': 0.16; 'header:In-Reply-To:1': 0.22; 'thu,': 0.22; 'integer': 0.23; 'null': 0.23; 'subject:data': 0.26; 'regardless': 0.26; 'chris': 0.27; 'object': 0.27; 'message- id:@mail.gmail.com': 0.28; 'subject:?': 0.29; 'useless': 0.31; 'does': 0.31; 'called': 0.32; 'to:addr:python-list': 0.32; 'legally': 0.33; "isn't": 0.34; 'difference': 0.35; 'point': 0.35; 'subject:What': 0.35; 'subject:use': 0.35; 'quite': 0.36; 'allow': 0.36; 'rather': 0.36; 'some': 0.37; 'received:209.85': 0.37; 'useful': 0.37; 'either': 0.37; 'received:google.com': 0.38; 'goes': 0.38; 'but': 0.38; 'hold': 0.39; 'somewhat': 0.39; 'to:addr:python.org': 0.39; 'received:209': 0.39; 'header:Received:5': 0.40; '2011': 0.62; 'special': 0.66; 'paper': 0.68; 'concept': 0.73; 'acts': 0.77; 'received:209.85.210.174': 0.84; 'received:mail-iy0-f174.google.com': 0.84; 'subject:other': 0.84; 'tied': 0.84 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:in-reply-to:references:date :message-id:subject:from:to:content-type; bh=SksgSHYnTuQX0JnOQ5LkfvMfIKrZQOsDXQ8BC6ziN+M=; b=rULNG6XTyJdLMN8b1f4XDXc7kyTDiz1BAG2ifu9IpMcjhWPQu1so9VICFNnxLheJFt YNr2U6Pb6cmhLHqHDnG2QvFMjms24VTnoNY8ve5dw61KnZWGSbup34zSpMmAr76zsTM9 lAQrL5opctPIz0N80w/JxFjacwyAdj7tEfPcQ= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=r40oHlh6AkGRzW1SKcT1wuZ3AFOBTnsHd2/rZBda2qn2rT1q2LCgD2fVKVB8nky6fd f5Pz3EoHQEGyaMcSq3EDatuGpwMw6y76N7Fezv511bdwU8B9sm/JROAGfTJlca7zm6lZ O/L7+yHshJT5qtKJaHvLrK5lkgVaip+CHxtM0= MIME-Version: 1.0 In-Reply-To: <87mxj2f8f4.fsf@benfinney.id.au> References: <4dbd1dbf$0$29991$c3e8da3$5496439d@news.astraweb.com> <77f64071-b288-404c-8280-b2c61ba77f06@n10g2000yqf.googlegroups.com> <4dc12fb4$0$29991$c3e8da3$5496439d@news.astraweb.com> <87mxj2f8f4.fsf@benfinney.id.au> Date: Thu, 5 May 2011 12:43:04 +1000 Subject: Re: What other languages use the same data model as Python? From: Chris Angelico To: python-list@python.org Content-Type: text/plain; charset=ISO-8859-1 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: 17 NNTP-Posting-Host: 82.94.164.166 X-Trace: 1304563387 news.xs4all.nl 81474 [::ffff:82.94.164.166]:52517 X-Complaints-To: abuse@xs4all.nl Xref: x330-a1.tempe.blueboxinc.net comp.lang.python:4687 On Thu, May 5, 2011 at 7:43 AM, Ben Finney wrote: > * that the paper tag is tied to only one object > > * that a paper tag tied to no object is rather useless > > * that many paper tags can be tied to the same object I disagree minorly; a tag tied to no object is quite useful in some circumstances. You can ditch the concept by having a special object that's called "No Object" (Python does this, with None), or you can allow your tag to point nowhere (C does this, with null pointers). The difference is semantic; either way, your tag can point to any object or it can point nowhere. (Pike goes for a slightly different approach; any variable, regardless of its stated types, may legally hold the integer 0. It acts somewhat as a null pointer, but it isn't really.) Chris Angelico