From -8529119465887169835 X-Google-Thread: f78e5,174aa7b34b06a51 X-Google-Attributes: gidf78e5,public X-Google-Language: ENGLISH,ASCII-7-bit Path: g2news1.google.com!news3.google.com!news.glorb.com!newsgate.cistron.nl!peer.news.zetnet.net!194.159.246.34.MISMATCH!peer-uk.news.demon.net!kibo.news.demon.net!news.demon.co.uk!demon!stump.algebra.com!devnull From: hyrosen@mail.com (Hyman Rosen) Newsgroups: comp.std.c++ Subject: Re: Is this really unspecified behavior? Date: Sat, 24 Dec 2005 14:20:00 GMT Lines: 37 Sender: mail2news@demon.net Approved: fjh@cs.mu.oz.au (Fergus Henderson , moderator of comp.std.c++) Message-ID: <200512231746.jBNHk0uC040526@horus.isnic.is> References: <1132759176.368850.264850@g43g2000cwa.googlegroups.com> <1132933832.802917.153350@g14g2000cwa.googlegroups.com> <1133551647.532929.325730@z14g2000cwz.googlegroups.com> <1133583412.951239.208510@g49g2000cwa.googlegroups.com> <1133910546.716987.80030@g14g2000cwa.googlegroups.com> <0l5ep1ppfhdj5p1pcu7e4na4ub0vjajlq3@4ax.com> <200512201408.jBKE8g64093941@mailbox7.ucsd.edu> <1135116348.175747.219310@f14g2000cwb.googlegroups.com> <1135179561.238816.222930@g47g2000cwa.googlegroups.com> <7bRhIfBCg9qDFwwW@robinton.demon.co.uk> NNTP-Posting-Host: news.news.demon.net Mime-Version: 1.0 Content-Type: text/plain; format=flowed; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Trace: news.demon.co.uk 1135434008 2824 158.152.254.254 (24 Dec 2005 14:20:08 GMT) X-Complaints-To: abuse@demon.net NNTP-Posting-Date: Sat, 24 Dec 2005 14:20:08 +0000 (UTC) X-Robomod: STUMP, ichudov@algebra.com (Igor Chudov) X-User-Agent: Mozilla Thunderbird 1.0.7 (Windows/20050923) X-Accept-Language: en-us, en X-Virus-Scanned: amavisd-new at cs.mu.OZ.AU X-Received: (from fjh@localhost) by mulga.cs.mu.OZ.AU (8.12.10+Sun/8.12.9/Submit) id jBOEK0TF023061; Sun, 25 Dec 2005 01:20:00 +1100 (EST) X-Path: comp-std-cpp-robomod!not-for-mail X-Delivered-To: std-c++@ucar.edu X-Authentication-Warning: mulga.cs.mu.OZ.AU: fjh set sender to devnull@stump.algebra.com using -f X-Newsgroups: comp.std.c++ Xref: g2news1.google.com comp.std.c++:2902 Francis Glassborow wrote: > It also breaks implementations, and ones that have excellent optimisers > may be broken in ways that require a major redesign of the optimiser. Again, I point out that optimizers are perfectly capable of dealing with sequences of ststements. It would be hard to characterize as "excellent" an optimizer which could not do so. Therefore, it is difficult to see how requiring a particular sequence of evaluations in an expression would break an optimizer. After all, I can rewrite an expression to make the order explicit. If I have int a(), b(); void f(int, int); f(a(), b()); then I can do const int &va = a(); const int &vb = b(); f(va, vb); If I have (the currently undefined) extern int a[], i; a[i++] = ++i; then I can do i++; int &ra = a[i]; ++i; ra = i; So unless we have this mythical smart/stupid optimizer which is brilliant in the first cases and clueless in the second, nothing is going to break; --- [ 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 ]