From 9205970296398903085 X-Google-Thread: f78e5,174aa7b34b06a51 X-Google-Attributes: gidf78e5,public X-Google-Language: ENGLISH,ASCII-7-bit Path: g2news1.google.com!news4.google.com!border1.nntp.dca.giganews.com!nntp.giganews.com!local01.nntp.dca.giganews.com!nntp.speakeasy.net!news.speakeasy.net.POSTED!not-for-mail NNTP-Posting-Date: Tue, 29 Nov 2005 09:20:14 -0600 Return-Path: X-Authentication-Warning: mulga.cs.mu.OZ.AU: fjh set sender to devnull@stump.algebra.com using -f X-Robomod: STUMP, ichudov@algebra.com (Igor Chudov) Delivered-To: std-c++@ucar.edu From: wade@stoner.com Newsgroups: comp.std.c++ Subject: Re: Is this really unspecified behavior? Organization: http://groups.google.com Message-ID: <1133275168.978618.68440@g47g2000cwa.googlegroups.com> References: <1132629737.664847.151630@o13g2000cwo.googlegroups.com> <1132722639.345095.296070@f14g2000cwb.googlegroups.com> <200511231401.jANE1BuC092897@horus.isnic.is> <37hco1hvfg2s43q2dv3003her7im99airg@4ax.com> <200511251438.jAPEcLuC052298@horus.isnic.is> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" X-Complaints-To: groups-abuse@google.com User-Agent: G2/0.2 X-HTTP-UserAgent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.1.4322; .NET CLR 2.0.50215; InfoPath.1),gzip(gfe),gzip(gfe) Complaints-To: groups-abuse@google.com Injection-Info: g47g2000cwa.googlegroups.com; posting-host=65.16.217.10; posting-account=1rcVOQwAAACiq302N7tDjZ9huexzBBxn X-Greylisting: NO DELAY (Relay+Sender autoqualified); processed by UCSD_GL-v2.1 on mailbox8.ucsd.edu; Tue, 29 November 2005 06:39:35 -0800 (PST) X-Spamscanner: mailbox8.ucsd.edu (v1.6 Aug 4 2005 15:27:38, -2.6/5.0 3.0.4) X-MailScanner: PASSED (v1.2.8 61630 jATEdYp0062544 mailbox8.ucsd.edu) X-Virus-Scanned: amavisd-new at ucar.edu X-Virus-Scanned: amavisd-new at cs.mu.OZ.AU Approved: Fergus Henderson , moderator of comp.std.c++ X-Virus-Scanned: amavisd-new at cs.mu.OZ.AU Date: Tue, 29 Nov 2005 09:12:51 CST Lines: 39 NNTP-Posting-Host: 65.182.171.162 X-Trace: sv3-U31Ya9rZ67volTt9ChSTCVZypEifWkVawXIM5UQmcJsA6kRQb6GKLOwGdurwrdyus5spNzIlNtHaIb1!vpAAgoKKq9yDUmum4anMU7B2z3DItAeOFGxYmwrBMQkazCRMkUum27GUIFt5hwI3VjpXPP37TYjL!3yj+q0W6cUinXNSPY3ZA/lR2tssWYswDhgTdqIM6wA== X-Complaints-To: abuse@speakeasy.net X-DMCA-Complaints-To: abuse@speakeasy.net X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly X-Postfilter: 1.3.32 Xref: g2news1.google.com comp.std.c++:2626 Hyman Rosen wrote: > We want to specify the exact > meaning of language constructs, Very often that is true. But which standard have you been reading? I'd argue that almost the entire libraries section goes out of its way to specify as little of the meaning as it can get away with, so that competing vendors can actually compete. Even the core language is full of cases where exact meanings could have been specified, but were left implementation-defined, or undefined. My gut feeling is that most of these cases are there specifically to give vendors freedom (to optimize, to build a simpler compiler, ...). Assuming vendors are responsive to their market, (sometimes this is a bit of a stretch ;-), the market is more interested in speed than in exact meaning. I see compilers offering 'restrict' or 'fast but sloppy floating point math' as options (or even defaults). I don't see options that enable a strict evaluation order. We could have had a language that told us the value of 'b' - 'a'. Instead we got a language where it is implementation-defined, and { char v='a'; v++; } is undefined. > not their implementation. But with a language that lets you get this close to the metal, a great deal of the implementation is observable (just not in the standard's sense of observable behavior). --- [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.jamesd.demon.co.uk/csc/faq.html ]