220 19954 <0FD6863F-4615-4A5C-867E-50F561844665@gmail.com> article Path: news.gmane.org!not-for-mail From: David Krauss Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Address of a reference: determining the value category of what it refers? Date: Sat, 22 Aug 2015 09:37:36 +0800 Lines: 104 Approved: news@gmane.org Message-ID: <0FD6863F-4615-4A5C-867E-50F561844665@gmail.com> References: <76fe342f-3342-4355-af20-1c41b21e54aa@isocpp.org> <1115b787-4cfd-4052-9f49-ece9c4bdf2ec@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 (Mac OS X Mail 8.2 \(2098\)) Content-Type: multipart/alternative; boundary="Apple-Mail=_582A9A05-5F6D-4BCA-821D-D4FB888C917A" X-Trace: ger.gmane.org 1440207470 21263 80.91.229.3 (22 Aug 2015 01:37:50 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sat, 22 Aug 2015 01:37:50 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCW25A7E3QCRBZ5E36XAKGQEC7GY5WA@isocpp.org Sat Aug 22 03:37:44 2015 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ig0-f197.google.com ([209.85.213.197]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1ZSxke-0005Oy-OZ for gclcip-std-proposals@m.gmane.org; Sat, 22 Aug 2015 03:37:44 +0200 Original-Received: by igcse8 with SMTP id se8sf52540332igc.1 for ; Fri, 21 Aug 2015 18:37:43 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:content-type:message-id:mime-version :subject:date:references:to:in-reply-to:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=Fpv1ZiuNAFcW158C0aFyIUIX1AJS52oPF9zJOJfjQz0=; b=Z+wNdBxhd/Jh/CMQvx4Fv/ZCU/Ik/7f4Y+mop4dYoN8YtSFWKKl56fqiA/OMdr705T GC7Pt5nuW/EfuX4iS4x7CSjQthSrGim2dvuJUJqgCqdAwjoIorjyqV52L5Ekxok8HNTS 7Pt2TvRidMDdX8Tp8UN/0RRiKJqOJgDUk1M1lmaCA2G6ORtgluYAzqHPSMdkEaPB3dRM bpUk4B2/TaRHEVneb3DfyDzYMYRHkZaLPrf4bc4VzZgJXndyB8mKiqq9nnejuxg1HUYh swNyPybzxn6PRIYsbGIg+nKKTLEr7gqyecb663yj8NEnW6fu2KtLTcKl+zQXSVFXD17D GGsQ== X-Gm-Message-State: ALoCoQlvdNHUuaipHBYqPBFlFj5MhteYoOj2XVwasi/F7Z/C7njbtkxr/sdmwIlyrjx33rXB3JAC X-Received: by 10.182.48.232 with SMTP id p8mr9104546obn.43.1440207463899; Fri, 21 Aug 2015 18:37:43 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.50.73.129 with SMTP id l1ls652595igv.31.gmail; Fri, 21 Aug 2015 18:37:43 -0700 (PDT) X-Received: by 10.66.244.230 with SMTP id xj6mr23022389pac.53.1440207463218; Fri, 21 Aug 2015 18:37:43 -0700 (PDT) Original-Received: from mail-pd0-x22f.google.com (mail-pd0-x22f.google.com. [2607:f8b0:400e:c02::22f]) by mx.google.com with ESMTPS id b1si15777170pat.26.2015.08.21.18.37.43 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 21 Aug 2015 18:37:43 -0700 (PDT) Received-SPF: pass (google.com: domain of potswa@gmail.com designates 2607:f8b0:400e:c02::22f as permitted sender) client-ip=2607:f8b0:400e:c02::22f; Original-Received: by pdrh1 with SMTP id h1so32653693pdr.0 for ; Fri, 21 Aug 2015 18:37:43 -0700 (PDT) X-Received: by 10.70.23.196 with SMTP id o4mr22990823pdf.1.1440207462832; Fri, 21 Aug 2015 18:37:42 -0700 (PDT) Original-Received: from [172.20.10.2] ([121.54.44.93]) by smtp.gmail.com with ESMTPSA id wf3sm9215271pab.9.2015.08.21.18.37.40 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Fri, 21 Aug 2015 18:37:42 -0700 (PDT) In-Reply-To: X-Mailer: Apple Mail (2.2098) X-Original-Sender: potswa@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of potswa@gmail.com designates 2607:f8b0:400e:c02::22f as permitted sender) smtp.mailfrom=potswa@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-Spam-Checked-In-Group: std-proposals@isocpp.org 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:19954 Archived-At: --Apple-Mail=_582A9A05-5F6D-4BCA-821D-D4FB888C917A Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 > On 2015=E2=80=9308=E2=80=9322, at 9:21 AM, NDos Dannyu wrote: >=20 > 2015=EB=85=84 8=EC=9B=94 22=EC=9D=BC =ED=86=A0=EC=9A=94=EC=9D=BC =EC=98= =A4=EC=A0=84 10=EC=8B=9C 14=EB=B6=84 49=EC=B4=88 UTC+9, Richard Smith =EB= =8B=98=EC=9D=98 =EB=A7=90: > That's not correct. "const int &rcr(0)" implicitly creates a temporary ob= ject of type int and binds the reference to that object. (The reference bin= ding then extends the lifetime of that temporary object to the lifetime of = the reference.) > I'm speaking about what it means, not how it is implemented. Even if it = is implemented as it refers to a temporary object, it should be treated as = it doesn't refer to an object, I mean. It=E2=80=99s part of the meaning of the program, not an arbitrary implement= ation detail. Excerpt from my upcoming proposal, revising N4221: > Lifetime extension is a very old C++ feature, originating before ISO stan= dardization began. Initializing a const& reference variable from a function= result to avoid a copy has worked since references were introduced. =E2=80= =A6Temporaries all worked that way at first =E2=80=A6 During the drafting o= f the ARM (1988-1989), Stroustrup blessed the idea of early destruction of = temporary objects. =E2=80=A6 Basic interoperability required some form of l= ifetime extension rule. >=20 --=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/. --Apple-Mail=_582A9A05-5F6D-4BCA-821D-D4FB888C917A Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=UTF-8
On 2015=E2=80=9308= =E2=80=9322, at 9:21 AM, NDos Dannyu <ndospark320@naver.com> wrote:

2015=EB=85=84 8=EC=9B=94 22=EC= =9D=BC =ED=86=A0=EC=9A=94=EC=9D=BC =EC=98=A4=EC=A0=84 10=EC=8B=9C 14=EB=B6= =84 49=EC=B4=88 UTC+9, Richard Smith =EB=8B=98=EC=9D=98 =EB=A7=90:
That's not correct. "const= int &rcr(0)" implicitly creates a temporary object of type int and bin= ds the reference to that object. (The reference binding then extends the li= fetime of that temporary object to the lifetime of the reference.)
 I'm speaki= ng about what it means, not how it is implemented. Even if it is implemente= d as it refers to a temporary object, it should be treated as it doesn't re= fer to an object, I mean.

It=E2=80=99s part of the meaning of the program, not an arbitrary im= plementation detail. Excerpt from my upcoming proposal, revising N4221:

Lifetime extension is a very old = C++ feature, originating before ISO standardization began. Initializing a <= span style=3D"font-size: 11px; font-family: Courier; background-color: rgb(= 245, 245, 245);" class=3D"">const& reference variable from a fun= ction result to avoid a copy has worked since references were introduced. = =E2=80=A6Tem= poraries all worked that way at first =E2=80=A6 During the drafting of the = ARM (1988-1989), Stroustrup blessed the idea of early destruction of tempor= ary objects. =E2=80=A6 Basic interoperability required some form of lifetime ext= ension rule.


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