220 13753 article Path: news.gmane.org!not-for-mail From: =?ISO-8859-1?Q?Daniel_Kr=FCgler?= Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Proposing std::uninitialized_default / uninitialized_emplace algorithm Date: Wed, 8 Oct 2014 11:10:03 +0200 Lines: 47 Approved: news@gmane.org Message-ID: References: <201410072114.05963.marc.mutz@kdab.com> <5434AAA1.1090507@gmail.com> <835B0691-50CD-490A-86DF-83A709CC550D@gmail.com> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable X-Trace: ger.gmane.org 1412759418 24052 80.91.229.3 (8 Oct 2014 09:10:18 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 8 Oct 2014 09:10:18 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCT7RVFA4QORB2762OQQKGQEIQCQFPA@isocpp.org Wed Oct 08 11:10:09 2014 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-vc0-f200.google.com ([209.85.220.200]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1XbnG1-0007Oo-B2 for gclcip-std-proposals@m.gmane.org; Wed, 08 Oct 2014 11:10:05 +0200 Original-Received: by mail-vc0-f200.google.com with SMTP id ij19sf17834330vcb.7 for ; Wed, 08 Oct 2014 02:10:04 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:date :message-id:subject:from:to:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:list-post:list-help:list-archive:list-subscribe :list-unsubscribe:content-type:content-transfer-encoding; bh=5dT6evDfqgn8nU/b8kP9NUx16UKiSmP44cLsGXNgVqM=; b=DNgHo++CXjgJrwHbVI6eXFLcV+K5S8nO8bO3H8vuhJbkEhR0vjpMa2N9P7L7cS288g ML/Ly6QjQOwwDeL/eXMdhjP2/Wi4yj+90jzxkaj6emEac55knhAas7nDKXN467PSIjzH DqbX4tbcxFAnK4pAdYDd2sFdi6JG4X2F5UZHrM8oCYZTH7Uc5qrr4AhGOjKRJgFl2mjf vBdtEM1QU2Ey7eqGhFiLDgoCpzxhYy0zV2RhekESPsf5ASkw3IxDCRl96HdZVDP5zYLX lpV3TDTkYPqY8dZumj4MkYLvjujZZHwhwHmBdyzj6Jxx/RCQVg82RmBtDUykSaNyZ7ZY Pucg== X-Gm-Message-State: ALoCoQnwFBN9x/32tAcbkP/Kk5WhFtMANsNBtDkCu5t7Jy1DdEu5pUvLun6664LaHtiw4GNh3b25 X-Received: by 10.236.151.75 with SMTP id a51mr5765319yhk.45.1412759404444; Wed, 08 Oct 2014 02:10:04 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.50.137.65 with SMTP id qg1ls3624598igb.44.canary; Wed, 08 Oct 2014 02:10:03 -0700 (PDT) X-Received: by 10.42.63.197 with SMTP id d5mr11393875ici.75.1412759403639; Wed, 08 Oct 2014 02:10:03 -0700 (PDT) Original-Received: from mail-ig0-x229.google.com (mail-ig0-x229.google.com [2607:f8b0:4001:c05::229]) by mx.google.com with ESMTPS id lz10si2140022icc.9.2014.10.08.02.10.03 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 08 Oct 2014 02:10:03 -0700 (PDT) Received-SPF: pass (google.com: domain of daniel.kruegler@gmail.com designates 2607:f8b0:4001:c05::229 as permitted sender) client-ip=2607:f8b0:4001:c05::229; Original-Received: by mail-ig0-f169.google.com with SMTP id uq10so8776709igb.0 for ; Wed, 08 Oct 2014 02:10:03 -0700 (PDT) X-Received: by 10.50.108.72 with SMTP id hi8mr4209921igb.39.1412759403325; Wed, 08 Oct 2014 02:10:03 -0700 (PDT) Original-Received: by 10.107.42.67 with HTTP; Wed, 8 Oct 2014 02:10:03 -0700 (PDT) In-Reply-To: <835B0691-50CD-490A-86DF-83A709CC550D@gmail.com> X-Original-Sender: daniel.kruegler@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of daniel.kruegler@gmail.com designates 2607:f8b0:4001:c05::229 as permitted sender) smtp.mail=daniel.kruegler@gmail.com; dkim=pass header.i=@gmail.com; dmarc=pass (p=NONE dis=NONE) header.from=gmail.com Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Google-Group-Id: 399137483710 List-Post: , List-Help: , List-Archive: List-Subscribe: , List-Unsubscribe: , Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:13753 Archived-At: 2014-10-08 10:25 GMT+02:00 Miro Knejp : > On 08 Oct 2014, at 05:08 , John Bytheway wrote: > >> On 2014-10-07 15:20, Daniel Kr=FCgler wrote: >>> I have strong concerns in regard to emplace in that context. Basically >>> everywhere "emplace" means a potential move of the provided arguments >>> to construct a single object. This won't work for a potential >>> multi-construction operation except for special cases (like empty >>> packs or packs of lvalues to const). People will easily get that >>> wrong. If you insist on copying the arguments, you could name it >>> emplace_copy and ensure that the argument pack refers to references to >>> const. > > In the context of the standard library functions labeled "emplace" simply= do in-place construction at the destination >location. Yes, I'm aware of that. >What happens to the arguments is solely the responsibility of the invoked = constructor. I'm not denying that, but in the existing contexts of "emplace" functions the potential harm related to multiple references of the same arguments to constructed objects does not occur. > If you construct multiple >objects with the same arguments you better use= constructors that behave well in that scenario. But you probably do >want = to receive arguments as lvalue references in this case just to be safe. I do not recognize any difference of this response compared to the arguments that I presented against using the name emplace here. It would be misleading to use the same name for things that have very difference semantics. - Daniel --=20 ---=20 You received this message because you are subscribed to the Google Groups "= ISO C++ Standard - Future Proposals" group. To unsubscribe from this group and stop receiving emails from it, send an e= mail to std-proposals+unsubscribe@isocpp.org. To post to this group, send email to std-proposals@isocpp.org. Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposa= ls/. .