From -7620941361567179521 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,10e355266b6fd117 X-Google-Attributes: gidf78e5,public X-Google-Thread: fc772,10e355266b6fd117 X-Google-Attributes: gidfc772,public X-Google-ArrivalTime: 2002-05-28 08:52:11 PST Path: archiver1.google.com!news1.google.com!newsfeed.stanford.edu!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!feed.news.qwest.net!namche.sun.com!news2me.EBay.Sun.COM!engnews1.eng.sun.com!taumet!clamage From: gneppert@web.de (McNepp) Newsgroups: comp.std.c++,comp.lang.c++.moderated Subject: Re: A humble attempt to suggest alignment support for C++ Date: 28 May 2002 15:47:45 GMT Organization: http://groups.google.com/ Lines: 56 Approved: stephen.clamage@sun.com (comp.std.c++) Message-ID: <53e3f3b2.0205270557.bdd703d@posting.google.com> References: <3CEA1A08.C6D95CC7@lmf.ericsson.se> NNTP-Posting-Host: taumet.eng.sun.com X-NNTP-Posting-Host: netlab.cs.rpi.edu X-Original-Date: 27 May 2002 06:57:01 -0700 X-Submission-Address: c++-submit@netlab.cs.rpi.edu X-Auth: PGPMoose V1.1 PGP comp.lang.c++.moderated iQBVAwUAPPLweUHMCo9UcraBAQEpPQH/YXcTETmekAiSygarEc8dWgWkWuX5KrQU xIhZsxE738qFVa7x/oppNk1/m1rlZSJ5lPojoOvZqLIbp6BwyvdtQg== =gQTF X-Approved-For-Group: jep@[151.161.11.6] comp.lang.c++.moderated X-Scanned-By: MIMEDefang 2.3 (www dot roaringpenguin dot com slash mimedefang) Content-Length: 1789 X-Status: $$$$ X-UID: 0000000001 Originator: clamage@taumet Xref: archiver1.google.com comp.std.c++:11602 comp.lang.c++.moderated:44057 Attila Feher wrote in message news:<3CEA1A08.C6D95CC7@lmf.ericsson.se>... > > > Motto: > ------ > > Dynamic memory allocation is expensive. To pay for it, just to get > right alignment is silly. > > > Motivation: > ----------- > > C++ programmers many times face the issue of being able to create fixed > capacity, dynamic sized sequential containers. Right now, with current > language features such a container can only be implemented using dynamic > memory allocation, like vector. But in many cases, such an allocation > is an overkill. > Yes, portable support for alignment is long overdue. But why not keep it as simple as possible? We want this declaration: char buffer[ count * sizeof(T) ]; to be a suitably aligned buffer for any type T. So what is really needed is just a simple specifier (e.g. "max_align") that does the trick: char max_align buffer[ count * sizeof(T) ]; Now we can safely cast this buffer to a T-array, using two static_casts... which immediately triggers the question: Why not skip the new keyword altogether and even get rid of one of the static_casts? What about allowing this syntax: void buffer[ count * sizeof(T) ]; This generic buffer can be safely cast (with one simple static_cast) to any type T. No new keywords needed, simple and self-explanatory, isn't it? [ Send an empty e-mail to c++-help@netlab.cs.rpi.edu for info ] [ about comp.lang.c++.moderated. First time posters: do this! ] [ 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 ]