From -5054760496038252562 X-Google-Thread: f78e5,99f1efda99846e15,start X-Google-Attributes: gidf78e5,public X-Google-Language: ENGLISH,ASCII-7-bit Path: g2news1.google.com!news2.google.com!proxad.net!news.cs.univ-paris8.fr!news.zanker.org!news.clara.net!wagner.news.clara.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: alexvn@big-foot.com ("Alex Vinokur") Newsgroups: comp.std.c++ Subject: Custom allocator for vector Date: Tue, 10 Aug 2004 17:18:53 GMT Lines: 39 Sender: mail2news@demon.net Approved: fjh@cs.mu.oz.au (Fergus Henderson , moderator of comp.std.c++) Message-ID: <2ns6efF45gptU1@uni-berlin.de> NNTP-Posting-Host: news.news.demon.net X-Trace: news.demon.co.uk 1092158339 26278 158.152.254.254 (10 Aug 2004 17:18:59 GMT) X-Complaints-To: abuse@demon.net NNTP-Posting-Date: Tue, 10 Aug 2004 17:18:59 +0000 (UTC) X-Robomod: STUMP, ichudov@algebra.com (Igor Chudov) X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2800.1441 X-Priority: 3 X-Spam-Checker-Version: SpamAssassin 2.60-mulga_r1 (1.212-2003-09-23-exp) on mulga.cs.mu.OZ.AU X-Orig-X-Trace: news.uni-berlin.de oLdMYPvhAoPZQJsf63T51QjET6pEflD5QXRwbbgf5i0Lj63eo= X-Spam-Status: No, hits=-4.2 required=5.2 tests=BAYES_00,PRIORITY_NO_NAME autolearn=no version=2.60-mulga_r1 X-MSMail-Priority: Normal X-Received: (from fjh@localhost) by mulga.cs.mu.OZ.AU (8.12.10+Sun/8.12.9/Submit) id i7AHIr1b004076; Wed, 11 Aug 2004 03:18:53 +1000 (EST) X-Path: comp-std-cpp-robomod!not-for-mail X-Spam-Level: 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-Newsreader: Microsoft Outlook Express 6.00.2800.1437 X-Newsgroups: comp.std.c++ Xref: g2news1.google.com comp.std.c++:1628 Different compilers produce quite different behavior with the same custom allocator. Here is the Nicolai M. Josuttis' allocator code sample (for vector) with cosmetic changes added by me to profile the executable: http://groups.google.com/groups?threadm=2nrba8F3sq7sU1%40uni-berlin.de Here are run log files for the following compilers * GNU g++ : http://groups.google.com/groups?selm=2nrb31F3q19kU1%40uni-berlin.de * Microsoft C++ : http://groups.google.com/groups?selm=2nrbdaF3orecU1%40uni-berlin.de * Borland C++ : http://groups.google.com/groups?selm=2nrbe9F3ta94U1%40uni-berlin.de We can see that * GNU g++ 3.3.1 doesn't invoke construct() and destroy(); * Microsoft C++ 13.00 and Borland C++ 5.5.1 do invoke construct() and destroy(). We can see also that behavior of Microsoft C++ 13.00 and Borland C++ 5.5.1 is quite different; for instance, Borland C++ allocates memory for 256 elements, Microsoft C++ allocates memory for small number of elements. So, behavior of a custom allocator is significantly compiler-dependent. The question is what can one achieve using a _custom_ allocator? The more specific question: do we need construct() and destroy() indeed? For instance, g++ doesn't use them. -- Alex Vinokur http://mathforum.org/library/view/10978.html http://sourceforge.net/users/alexvn --- [ 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 ]