220 35154 <3545851.gG3tdlLWKt@tjmaciei-mobl1> article Path: news.gmane.org!.POSTED!not-for-mail From: Thiago Macieira Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: std::vector must have strong move guarantees. 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[78.47.120.188]) by mx.google.com with ESMTP id r20si3837223wmb.17.2017.10.30.12.19.52 for ; Mon, 30 Oct 2017 12:19:52 -0700 (PDT) Received-SPF: pass (google.com: domain of thiago@macieira.org designates 78.47.120.188 as permitted sender) client-ip=78.47.120.188; Original-Received: from tjmaciei-mobl1.localnet (fmdmzpr03-ext.fm.intel.com [192.55.54.38]) by gondolin.macieira.info (Postfix) with ESMTPSA id C25AF11B610 for ; Mon, 30 Oct 2017 12:19:50 -0700 (PDT) In-Reply-To: <9044cb40-c9d7-4773-b2bd-536ed112bcbe@isocpp.org> X-Original-Sender: thiago@macieira.org X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of thiago@macieira.org designates 78.47.120.188 as permitted sender) smtp.mailfrom=thiago@macieira.org 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:35154 Archived-At: On segunda-feira, 30 de outubro de 2017 12:06:56 PDT tower120@gmail.com wrote: > So, move = faster copy ... Is this defined somewhere in standard? I thought > about move semantic rather as Rust's move - we work with the same object, > but now just move to another space, faster/slower is just optimization > details. This discussion is getting blocked by the identity of an object. If an object is the same object if and only if it has the same pointer address, then std::vector always copies when it reallocates. Whether it calls the move constructor or not is a detail. If an object is the same provided it was always moved from another, then std::vector could still have the same original object. This is of relevance for objects whose copy constructor needs to allocate memory (like pimpl objects), in which case you can tell whether it's the same original object by looking at those pointers. -- Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org Software Architect - Intel Open Source Technology Center -- 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 email to std-proposals+unsubscribe@isocpp.org. To post to this group, send email to std-proposals@isocpp.org. To view this discussion on the web visit https://groups.google.com/a/isocpp.org/d/msgid/std-proposals/3545851.gG3tdlLWKt%40tjmaciei-mobl1. .