From 4722835142752540906 X-Google-Thread: f78e5,4ae4d1cd1dd2d66c X-Google-NewGroupId: yes X-Google-Attributes: gid7894ca11fe,domainid0,public,usenet X-Google-Language: ENGLISH,ASCII Received: by 10.68.129.169 with SMTP id nx9mr1121531pbb.2.1333052281063; Thu, 29 Mar 2012 13:18:01 -0700 (PDT) MIME-Version: 1.0 Path: z9ni16125pbe.0!nntp.google.com!news2.google.com!feed-C.news.volia.net!volia.net!news2.volia.net!feed-A.news.volia.net!news.musoftware.de!wum.musoftware.de!news.albasani.net!.POSTED!not-for-mail From: =?ISO-8859-1?Q?Daniel_Kr=FCgler?= Newsgroups: comp.std.c++ Subject: Re: Request =?ISO-8859-1?Q?f=F6r_std=3A=3Avector_and_possi?= =?ISO-8859-1?Q?bly_others=3A_minimal_initalization?= Date: Thu, 29 Mar 2012 13:17:58 -0700 (PDT) Organization: A noiseless patient Spider Lines: 42 Sender: std-cpp-request@vandevoorde.com Approved: james.dennett@gmail.com Message-ID: References: <3008757.1215.1332274822853.JavaMail.geo-discussion-forums@pbjv6> <4991d0ff-8c66-41d2-a04d-22a6acce6065@s9g2000pba.googlegroups.com> <25560658.357.1332969573044.JavaMail.geo-discussion-forums@ynuu12> NNTP-Posting-Host: DBpZN7GUJUoN3mMBw7ToD6q+iS05NNnW481mYyA0rk0= X-Trace: news.albasani.net pd0ORQqR9gryslP0jI72N9D7i86yCPDs9Te6ars08aBaKL5sasSHlbl0Pp1w8ZaQ6QI6WYWXsFD6OSTNa+zPXQ== X-Complaints-To: abuse@albasani.net NNTP-Posting-Date: Thu, 29 Mar 2012 20:18:00 +0000 (UTC) X-Mailer: Perl5 Mail::Internet v2.05 X-Submission-Address: std-cpp-submit@vandevoorde.com Cancel-Lock: sha1:XoPzL4wfv3c5dhVp7tQqKJVXGcw= X-Original-Date: Thu, 29 Mar 2012 21:33:45 +0200 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Am 29.03.2012 21:28, schrieb Pedro Lamar�o: > > Em sexta-feira, 23 de mar�o de 2012 21h11min22s UTC-3, Kevin McCarty escreveu: > >> Case 1) Interfacing with old (C?) code that will initialize a >> contiguous block of memory in-place. One can't always expect that >> existing code can be rewritten to take a vector and call push_back or >> emplace_back on it. >> >> E.g., supposing the existence of something called std::no_initialize >> (whatever that might be) >> >> // some old 3rd-party library function; maybe it calls fread()? >> extern "C" initialize_mem(size_t sz, int * mem); >> >> vector ints(42, std::no_initialize); >> initialize_mem(ints.size(), ints.data()); > > > In the OP's use case, there is a known amount of "results" for which space must be allocated. > > And it is desired to have space allocated, but no constructors run on it. > > Isn't uninitialized-land where operator new and std::allocator live? Why not go there? Yes, this is certainly possible. Just provide an allocator, where construct (and presumably also destroy) is basically a no-op. I certainly would not recommend this technique generally, because it requires a cool head and a stable nervous system ;-) Greetings from Bremen, Daniel Kr�gler -- [ comp.std.c++ is moderated. To submit articles, try posting with your ] [ newsreader. If that fails, use mailto:std-cpp-submit@vandevoorde.com ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.comeaucomputing.com/csc/faq.html ]