220 16282 article Path: news.gmane.org!not-for-mail From: Scott Prager Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Pointers to members of unknown class Date: Mon, 16 Feb 2015 06:58:57 -0800 (PST) Lines: 137 Approved: news@gmane.org Message-ID: References: <9b03a820-0ac5-4931-9825-b2fc9ef893f9@isocpp.org> <885c1fbd-8701-4f70-b7ad-89ee9104f42d@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_1233_1971991114.1424098737328" X-Trace: ger.gmane.org 1424098755 23214 80.91.229.3 (16 Feb 2015 14:59:15 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Mon, 16 Feb 2015 14:59:15 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCU6PTE6UUGBBMMLRCTQKGQER4ZJA4Q@isocpp.org Mon Feb 16 15:59:00 2015 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ie0-f199.google.com ([209.85.223.199]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1YNN8V-0002lM-IO for gclcip-std-proposals@m.gmane.org; Mon, 16 Feb 2015 15:58:59 +0100 Original-Received: by iecrl12 with SMTP id rl12sf226069153iec.0 for ; Mon, 16 Feb 2015 06:58:58 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=date:from:to:message-id:in-reply-to:references:subject:mime-version :content-type:x-original-sender:reply-to:precedence:mailing-list :list-id:list-post:list-help:list-archive:list-subscribe :list-unsubscribe; bh=sDrv7V5SOEq1DgNmTP+6g3p19+PAnQLctrmpb74Iw1w=; b=mnZc8/u1OQ2f65PURBhgv5FT+OIUbJGSVxLwdxllvg2GD3DFksCrtrKxrLUncLfAN5 ahDQgEiF1fELkkZLygAHDCuOMxJPBnah75RQ6VY7EhcmLEHqzF0MeetzyFHrZS7y2XY2 xog61DtDn5CuXAOaA/cVigQEey2SUwD74fxZAdZaYQeadfFQ1y3fBr96lNcBL+yKtmsG uNg9++Zh3F8GIovd88FRH7/78Bmvi2/pYycfsUKAa4fLeN+mlk3MEoSs/pBYgpukIHRY CKgDFK7VpIidbtZ9aqOmzMBT45tnSB+FqpWE5sQPceGdMid/Rt0YrKfxXdVNxuBUNOM/ btxQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:date:from:to:message-id:in-reply-to:references :subject:mime-version:content-type:x-original-sender:reply-to :precedence:mailing-list:list-id:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=sDrv7V5SOEq1DgNmTP+6g3p19+PAnQLctrmpb74Iw1w=; b=f3VpLMfIk+xnNUC+xqzUP4DNHw8pYE5uwZwoBELmxAhPIkLxmQ2DowvyeZAYMLyUcP X7bh0QBGQDdGBwPZKAbZSJeyGBNECx7ObnAg5AGUtKYMRThrE1MuKWxZWFkxBV1d6YZ4 p+S/2fVBHP2t5Hea2CGelrhwE4XcMpJnFcoCuYJ8idxdqJBA93IVJ+bl2IJd1mAIme+N JCZSxozyYpaXLvVRn9etj7LEKqupV9We+k22aYYU2P8xkImEsk896ldJ5xvn27hFFj7X aba0rK5veqPfBoPNRDFfLCs3jgiIY+LTcsfwDIu4Qn3fa2eXB5skzbsBD6oCgQAEGR1C WKhQ== X-Gm-Message-State: ALoCoQn8kYm7n9SIDi2RcIcWgsINKL0s5/6sRcZczv2ZSlSnZ2z40d5UnFHlxcrLOqHk2J2ysaBl X-Received: by 10.182.224.169 with SMTP id rd9mr20121926obc.41.1424098738392; Mon, 16 Feb 2015 06:58:58 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.140.94.170 with SMTP id g39ls2491447qge.28.gmail; Mon, 16 Feb 2015 06:58:57 -0800 (PST) X-Received: by 10.140.96.202 with SMTP id k68mr279998qge.24.1424098737620; Mon, 16 Feb 2015 06:58:57 -0800 (PST) In-Reply-To: <885c1fbd-8701-4f70-b7ad-89ee9104f42d@isocpp.org> X-Original-Sender: SplinterOfChaos@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:16282 Archived-At: ------=_Part_1233_1971991114.1424098737328 Content-Type: multipart/alternative; boundary="----=_Part_1234_1139528847.1424098737328" ------=_Part_1234_1139528847.1424098737328 Content-Type: text/plain; charset=UTF-8 On Monday, February 16, 2015 at 5:58:52 AM UTC-5, Markus Grech wrote: > > I have updated the proposal, feedback would be very appreciated. > > https://docs.google.com/document/d/1B4zWiym1twufigKA4RSXYR5xU4g32EJ8XNl_bzFtX08/edit?usp=sharing > One possible use-case that I don't see in this proposal: struct X { int mem; }; struct Y { int mem; }; int void::* p = X::mem; auto xp = static_cast(p); // (1) auto yp = static_cast(p); // (2) Obviously, *(1) *should be valid, and you describe such a round trip in the proposal, but what about *(2)*? Certainly not valid, but I don't see anything prohibiting it. -- --- 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. Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposals/. ------=_Part_1234_1139528847.1424098737328 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable


On Monday, February 16, 2015 at 5:58:52 AM UTC-5, = Markus Grech wrote:

One possible use-case that I don't see in this propo= sal:

struct X { int mem; };
struct Y { int mem; };


int void::* p =3D X::mem;
<= span style=3D"color: #008;" class=3D"styled-by-prettify">auto xp =3D static_cast<int X::*>(p= );  <= /span>// (1)
auto yp =3D static_cast<int Y::*>(p);  // (2)


Obviously, (1) sh= ould be valid, and you describe such a round trip in the proposal, but what= about (2)?
Certainly not valid, but I don't see anything = prohibiting it.

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