220 34257 article Path: news.gmane.org!.POSTED!not-for-mail From: Ville Voutilainen Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Proposal to add constructors to std::bad_alloc exception class. 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[209.85.220.41]) by mx.google.com with SMTPS id l125sor698390vkh.27.2017.09.01.13.45.35 for (Google Transport Security); Fri, 01 Sep 2017 13:45:35 -0700 (PDT) Received-SPF: pass (google.com: domain of ville.voutilainen@gmail.com designates 209.85.220.41 as permitted sender) client-ip=209.85.220.41; X-Received: by 10.31.109.3 with SMTP id i3mr1983994vkc.114.1504298734965; Fri, 01 Sep 2017 13:45:34 -0700 (PDT) Original-Received: by 10.103.103.135 with HTTP; Fri, 1 Sep 2017 13:45:34 -0700 (PDT) In-Reply-To: X-Original-Sender: ville.voutilainen@gmail.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=TypytRIr; spf=pass (google.com: domain of ville.voutilainen@gmail.com designates 209.85.220.41 as permitted sender) smtp.mailfrom=ville.voutilainen@gmail.com; dmarc=pass (p=NONE sp=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:34257 Archived-At: On 1 September 2017 at 23:42, Nevin Liber wrote: >> I have a follow-up question: did you consider the alternative where >> the caller of the new constructor must pass an rvalue reference >> to a std::string, in which case there would be most likely a much >> smaller allocation, as in the case of a dynamically >> allocated string that doesn't fit into SSO, there would be none, and >> in the SSO case, a very small allocation that >> is not dynamic? > > > I don't think an rvalue reference to a std::string helps. As was recently > pointed out to me [exception]p2: Each standard library class T that derives > from class exception shall have a publicly accessible copy constructor and a > publicly accessible copy assignment operator that do not exit with an > exception. > > std::string doesn't meet that requirement (and cannot, since we effectively > no long allow a reference counted std::string implementation as of C++11), > so bad_alloc cannot hold one. Just make the copy operation terminate() if it fails to copy a string. ;) Flippant ideas aside, this is a fairly important thing to consider in the scope of this proposal, good catc.. err, finding. -- 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. 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