220 37358 article Path: news.gmane.org!.POSTED!not-for-mail From: Hyman Rosen Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: `offsetof` in a macro-less, modular world Date: Fri, 16 Mar 2018 11:13:21 -0400 Lines: 67 Approved: news@gmane.org Message-ID: References: <2034613.rN3AoRdNao@tjmaciei-mobl1> <2319008.6H3YVR8kxN@tjmaciei-mobl1> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="001a1143dd1ebbef420567890d80" X-Trace: blaine.gmane.org 1521213101 32025 195.159.176.226 (16 Mar 2018 15:11:41 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Fri, 16 Mar 2018 15:11:41 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDKJJPVBQMKRBJ56V7KQKGQE56BHE3I@isocpp.org Fri Mar 16 16:11:37 2018 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-wr0-f199.google.com ([209.85.128.199]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1ewr17-0008Fq-8g for gclcip-std-proposals@m.gmane.org; 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[209.85.220.41]) by mx.google.com with SMTPS id r74sor317663wme.27.2018.03.16.08.13.42 for (Google Transport Security); Fri, 16 Mar 2018 08:13:42 -0700 (PDT) Received-SPF: pass (google.com: domain of hyman.rosen@gmail.com designates 209.85.220.41 as permitted sender) client-ip=209.85.220.41; X-Received: by 10.28.146.2 with SMTP id u2mr1884679wmd.79.1521213222152; Fri, 16 Mar 2018 08:13:42 -0700 (PDT) Original-Received: by 10.28.55.19 with HTTP; Fri, 16 Mar 2018 08:13:21 -0700 (PDT) In-Reply-To: <2319008.6H3YVR8kxN@tjmaciei-mobl1> X-Original-Sender: hyman.rosen@gmail.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=YA60HGlU; spf=pass (google.com: domain of hyman.rosen@gmail.com designates 209.85.220.41 as permitted sender) smtp.mailfrom=hyman.rosen@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE 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:37358 Archived-At: --001a1143dd1ebbef420567890d80 Content-Type: text/plain; charset="UTF-8" On Thu, Mar 15, 2018 at 8:05 PM, Thiago Macieira wrote: > > int A:: *int_in_A = &A::y; // just so we don't discuss arrays > just now > A B:: *A_in_B = &B::a; > int B:: *int_in_B = int_in_A + A_in_B; // syntax TBD Rather than inventing a new syntax, the obvious solution is to allow the creation of member pointers using a syntax that allows C designators to be used, instead of just *qualified-id*s. The code above would then just be struct A { int x[10]; }; struct B { A a; }; int B::*number_5 = &B::a.x[5]; -- 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/CAHSYqdbvMA-gv%2BeP1iu53J6pnLTmr9KjR4_0XJBnEsy5qth%3D%2BA%40mail.gmail.com. --001a1143dd1ebbef420567890d80 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
On T= hu, Mar 15, 2018 at 8:05 PM, Thiago Macieira <thiago@macieira.org&g= t; wrote:
=C2=A0 =C2=A0 =C2=A0 =C2=A0 int A:: *int_in_A =3D &A::y;=C2=A0 =C2=A0 = =C2=A0 // just so we don't discuss arrays just now
=C2=A0 =C2=A0 =C2=A0 =C2=A0 A B:: *A_in_B =3D &B::a;
=C2=A0 =C2=A0 =C2=A0 =C2=A0 int B:: *int_in_B =3D int_in_A + A_in_B;=C2=A0 = // syntax TBD

Rather than inventing a new syntax, the = obvious solution is to allow the creation of
member pointers using a syn= tax that allows C designators to be used, instead of
just qualified-i= ds.=C2=A0 The code above would then just be

=C2=A0 =C2=A0 struct A { int x[10]; };
=C2=A0 =C2=A0 str= uct B { A a; };
=C2=A0 =C2=A0 int B::*number_5 =3D &B::a.x[5];

--
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To view this discussion on the web visit https://groups.google.com/a/isocpp.org/d/msgid/std-proposals/CAHSYqdbvMA= -gv%2BeP1iu53J6pnLTmr9KjR4_0XJBnEsy5qth%3D%2BA%40mail.gmail.com.
--001a1143dd1ebbef420567890d80-- .