220 35060 <2688395.4cN1N1XxoH@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, std::string attach/detach external buffer Date: Fri, 20 Oct 2017 13:12:13 -0700 Lines: 36 Approved: news@gmane.org Message-ID: <2688395.4cN1N1XxoH@tjmaciei-mobl1> References: Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" X-Trace: blaine.gmane.org 1508530351 24708 195.159.176.226 (20 Oct 2017 20:12:31 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Fri, 20 Oct 2017 20:12:31 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCB4TK757YBRBJNRVHHQKGQERCTE5CY@isocpp.org Fri Oct 20 22:12:25 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-wr0-f197.google.com ([209.85.128.197]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1e5deR-0004NZ-2I for gclcip-std-proposals@m.gmane.org; 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[78.47.120.188]) by mx.google.com with ESMTP id h43si1326232wrh.277.2017.10.20.13.12.21 for ; Fri, 20 Oct 2017 13:12:21 -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 (jfdmzpr04-ext.jf.intel.com [134.134.139.73]) by gondolin.macieira.info (Postfix) with ESMTPSA id 7CB5D11B4F6 for ; Fri, 20 Oct 2017 13:12:20 -0700 (PDT) In-Reply-To: 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:35060 Archived-At: On Friday, 20 October 2017 09:50:32 PDT Nicol Bolas wrote: > The other issue is how to deal with `basic_string` and its ability to use > small-string optimization. That is, if I have a 12-byte string and I > initialize an SSO `string` from it, when does my buffer get deleted? The > `basic_string` should not be required to keep my buffer around if the > number of characters fits into the SSO buffer. So we'd have to say that the > buffer could be deleted as recently as the call that consumes it. Right. Once you transfer ownership to the std type, it *owns* that buffer and has the ability to free it as soon as it wants to. using cstring = std::basic_string; auto str = cstring::from_raw_string(someBuf, someLen); if someLen < SSO threshold, one of two things can happen: 1) cstring points to your buffer, despite not needing to 2) cstring copies someBuf onto itself and frees your buffer using the mallocator Note, however, the consequence: char *ptr = cstring.detach_buffer(); may fail. -- 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/2688395.4cN1N1XxoH%40tjmaciei-mobl1. .