From -1219336029992471282 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,2340bb60e0f0f248 X-Google-Attributes: gidf78e5,public X-Google-ArrivalTime: 2002-02-15 09:21:01 PST Path: archiver1.google.com!news1.google.com!newsfeed.stanford.edu!logbridge.uoregon.edu!dispose.news.demon.net!news.demon.co.uk!demon!mail2news.demon.co.uk!not-for-mail From: Gabriel Dos Reis Newsgroups: comp.std.c++ Subject: Re: proposal for resolution of "valarray operator[] const returning value" (closed isuue 77) Date: Fri, 15 Feb 2002 17:20:16 GMT Organization: CMLA, ENS Cachan -- CNRS UMR 8536 (France) Approved: Fergus Henderson , moderator of comp.std.c++ Message-ID: References: X-Trace: mail2news.demon.co.uk 1013793623 mail2news:19865 mail2news mail2news.demon.co.uk X-Complaints-To: abuse@demon.net X-Mail2News-Path: news.demon.net!mulga.cs.mu.oz.au 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) Mime-Version: 1.0 (generated by tm-edit 7.106) Content-Type: text/plain; charset=US-ASCII NNTP-Posting-Date: Fri, 15 Feb 2002 17:11:27 +0000 (UTC) X-Newsreader: Gnus v5.6.45/Emacs 19.34 Lines: 86 Xref: archiver1.google.com comp.std.c++:9662 Markus Werle writes: | Gabriel Dos Reis wrote: | | > More importantly, it makes valarray<> unusable in most real world | > programs. There are plenty of numerical routines out there written in | > C and passing valarray<> data to them for inspection is not as trivial | > as it should have been or intented :-( | > | > FYI, the GCC/g++ changed that operator to return a const reference. | | Yes, I fell into the trap when gcc-compliant code did | not compile with intel's C++. | IMHO this is the wrong way to go either. I'm disposed to be convinced. | I dislike the freedom | gcc developers took without noticing me in the README. | ISO conformance is a must, so we must change the standard if it | does not fit, not our "private" library. ISO conformance isn't a goal in itself. The tool has no practical value if it can't be used. When a strict ISO conformance leads to unuable tool, then something must be done. That is why we DR submissions. I've choosed not to wait -- after several papers and discussions about the issue. Another example is accessiblity. A strict conformant implementation makes the helper classes unuable. | > | I for myself can think of a lot of cases in which I wished | > | to have all the functionality of valarray, but a return type of | > | const reference, (e.g. valarray > for | > | compressed matrices) | > | and so I propose an extension of valarray which | > | I think does not break existing, conformant code. | > | > I have trouble to conceive a real-world program which would be broken | > if that operator's return type were changed to const reference. So | > let keep it simple and straight. | | I disagree here. If you have concrete real-world examples, I would be very glad to discuss it. | Both ways have their pros and cons | and if You are honest they balance quite well. I don't know I'm supposed to take that. | Those who struggle with connection to fortran and C | need the reference (which speeds code by a factor of 10 or more) The valarray<> class was primary designed to serve also those people. | and those who have a Pentium 4 and the intel compiler | need the copy (sometimes), because this may speed up | by a factor of 10 or more due to funny register magic | I do not want to learn about. I'll ask again: Do you have a real world case where returning a const reference makes any difference in performance? [...] | Let us stop a never ending fruitless | discussion with a quite elegant whip. | | Have You any argument against my approach? Yes: It ignores reality. The issue isn't about Stellar Abstract Algebra. Would you mind to give us concrete example (i.e. a program) we can start with? Also, I find your posting unncessarily personnal and I'm surprised to fint it passed the moderation filter. -- Gabriel Dos Reis, dosreis@cmla.ens-cachan.fr --- [ 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.research.att.com/~austern/csc/faq.html ]