220 13362 <8C19FE11-C9BF-446D-8CFF-FEB52FEA546C@gmail.com> article Path: news.gmane.org!not-for-mail From: David Krauss Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Tighten rules for virtual override keyword combination Date: Tue, 30 Sep 2014 14:20:35 +0800 Lines: 57 Approved: news@gmane.org Message-ID: <8C19FE11-C9BF-446D-8CFF-FEB52FEA546C@gmail.com> References: <19267205-7e26-4c12-b9b4-f26ab2f99eb7@isocpp.org> <803262EF-88B4-40B0-AC9B-7C7356CDE56A@gmail.com> <54274B57.6040007@gmail.com> <8DC1AED8-83B6-453A-A93A-EAB6AF942968@gmail.com> <39638C85-5546-444B-A7AA-F873947777B4@gmail.com> <22C84181-5761-4744-AC90-6E252B5CB1E4@gmail.com> <9367C570-6D36-4E88-BFD3-85F5A632DEDE@gmail.com> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 (Mac OS X Mail 7.3 \(1878.6\)) Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable X-Trace: ger.gmane.org 1412058058 31721 80.91.229.3 (30 Sep 2014 06:20:58 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 30 Sep 2014 06:20:58 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCW25A7E3QCRBQMXVGQQKGQEOFNFZJY@isocpp.org Tue Sep 30 08:20:52 2014 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ie0-f198.google.com ([209.85.223.198]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1XYqnr-00011C-B6 for gclcip-std-proposals@m.gmane.org; Tue, 30 Sep 2014 08:20:51 +0200 Original-Received: by mail-ie0-f198.google.com with SMTP id tp5sf38526373ieb.9 for ; Mon, 29 Sep 2014 23:20:50 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:subject:from:in-reply-to:date :message-id:references:to:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:list-post:list-help:list-archive:list-subscribe :list-unsubscribe:content-type:content-transfer-encoding; bh=OnXVPVhYmxQDPmaC2dNqWNFAV9y5tigixlglDynI2f4=; b=XMjpmFi+QSJE5SUAFKQe1faXoNIwrOer0/1Lq3O0wrY01i8wX4dguWBOYLMbU96nD0 B64Sf8ZDRy9g2DQCVvTxhm6QnwlfiKEZ/Di8Nz+hHgX7Mgyrq0I7IWGw9hSAW14Pk/D2 tD8HYSaCGKk1i6Uvw47DKJNwYc2Q9e9yK9bQrR+NiS2dXGU4AdtnuXPvrYyWn3fZ1hm2 oMjeTO+N4oZKj2D8WWVoA9NL3wrQqJOQJRs5RbK3WccV5nNGtmxiwOSVkMS3FXdT2sEQ r2q2uZSn+WY/GjhkZxMcdS9nJ4cxDcNyzhX06vajyw4HLYcPrbX8fagyElx5pPqJp8Ix qASA== X-Gm-Message-State: ALoCoQl6S/pbmSR+C1n9+GB86USCoxEPAW7C2ZWLxHPgrx5ftKwpK/RhkfZh+Kl8ukxwJ3Fx2Tj/ X-Received: by 10.182.219.77 with SMTP id pm13mr36598473obc.37.1412058050218; Mon, 29 Sep 2014 23:20:50 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.50.114.10 with SMTP id jc10ls4837igb.4.gmail; Mon, 29 Sep 2014 23:20:49 -0700 (PDT) X-Received: by 10.67.3.162 with SMTP id bx2mr64984388pad.57.1412058049669; Mon, 29 Sep 2014 23:20:49 -0700 (PDT) Original-Received: from mail-pa0-x229.google.com (mail-pa0-x229.google.com [2607:f8b0:400e:c03::229]) by mx.google.com with ESMTPS id i4si4113339pbw.158.2014.09.29.23.20.49 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Mon, 29 Sep 2014 23:20:49 -0700 (PDT) Received-SPF: pass (google.com: domain of potswa@gmail.com designates 2607:f8b0:400e:c03::229 as permitted sender) client-ip=2607:f8b0:400e:c03::229; Original-Received: by mail-pa0-f41.google.com with SMTP id eu11so3577398pac.28 for ; Mon, 29 Sep 2014 23:20:49 -0700 (PDT) X-Received: by 10.70.37.208 with SMTP id a16mr22248580pdk.147.1412058049463; Mon, 29 Sep 2014 23:20:49 -0700 (PDT) Original-Received: from [172.20.10.2] ([121.54.54.153]) by mx.google.com with ESMTPSA id y11sm14068457pbv.54.2014.09.29.23.20.46 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Mon, 29 Sep 2014 23:20:48 -0700 (PDT) In-Reply-To: X-Mailer: Apple Mail (2.1878.6) 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:c03::229 as permitted sender) smtp.mail=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-Google-Group-Id: 399137483710 List-Post: , List-Help: , List-Archive: List-Subscribe: , List-Unsubscribe: , Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:13362 Archived-At: On 2014-09-29, at 11:37 PM, Ville Voutilainen = wrote: > On 29 September 2014 18:18, David Krauss wrote: >>> Or it demonstrates a very deliberate design choice, rather than a >>> fundamental misunderstanding. >> The deliberate choice *is* the misunderstanding. When one implements an = abstract class, s/he should read its documentation, or be familiar enough b= eforehand, to know its public interface. >=20 > I am not talking about a misunderstanding of any kind. I'm talking > about cases where it's necessary to hide a function in a base class, and = cases where people > know what they are doing and what the consequences are and how to allevia= te the consequences. The "consequences to be alleviated" are the consequences of a potential mis= understanding. Someone who is trying to implement the abstract class, but d= oesn't conceptually understand its public interface well enough to avoid tr= eading on it, is the idiot who whose error will be prevented by the legitim= ate design choice you've described. Such a misunderstanding seems so pathol= ogical to me as to indicate that such a person may not be competent to comp= lete their task anyway. This sort of error is completely different from get= ting a type or exception-specification wrong. I suppose the choice could be approached from the perspective of defensive = programming in a purely conceptual sense, in terms of what defective derive= d-class specifications potentially exist, without considering what people d= o or think. I don't subscribe to such philosophies, although allowing defec= tive specifications to be ruled out is usually a good thing, and reserving = a name from derived classes is certainly a reasonable feature. > I never suggested forbidding final without override as an alternative > for anything. You assumed it's what I was suggesting. > And whatever the alternative would've supposed to be in some hypothetical > world, those alternatives were not suggested strongly enough, or perhaps = at all, > so we didn't choose them. Changing such a decision will be hard. Yes, the ship has sailed. I find it hard to believe that "final implies ove= rride" simply never occurred to the designers though. --=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/. .