220 13239 article Path: news.gmane.org!not-for-mail From: "'Geoffrey Romer' via ISO C++ Standard - Future Proposals" Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Tighten rules for virtual override keyword combination Date: Sat, 27 Sep 2014 22:50:51 -0700 Lines: 108 Approved: news@gmane.org Message-ID: References: <19267205-7e26-4c12-b9b4-f26ab2f99eb7@isocpp.org> <803262EF-88B4-40B0-AC9B-7C7356CDE56A@gmail.com> <54274B57.6040007@gmail.com> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary=001a11c2fad0948494050419bb1a X-Trace: ger.gmane.org 1411883461 3438 80.91.229.3 (28 Sep 2014 05:51:01 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sun, 28 Sep 2014 05:51:01 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBD74DCN5SYHBBO6DT2QQKGQEXWOG5AY@isocpp.org Sun Sep 28 07:50:54 2014 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 1XY7Nl-0005A6-Ej for gclcip-std-proposals@m.gmane.org; Sun, 28 Sep 2014 07:50:53 +0200 Original-Received: by mail-ie0-f199.google.com with SMTP id rl12sf6366229iec.6 for ; Sat, 27 Sep 2014 22:50:52 -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:in-reply-to:references:date :message-id:subject:from: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; bh=7k2Sj10Am9v5zhIr+YC6q6mowyik+wXdV9H1358OlXU=; b=i5hF0YJaFgwRS2HjxrzCNmY+zFxpB+pXddUVpBpcSUhOf0/fDTL8YCYLXuCt9jtd6r SSN6N0gvtwrMfvEFpHcv9tsbVCb+GZ5W3O5E1lyvAPePlCgb+y+LWKSAr36y6Mg6xv/n uZKeq7M6CSts9j+jXnHIjpSO4hhuJ7sG7wDa2QokDEpmsxsUhMryr3z+RGWvT356n01w tZ2hZCUtImWPEbeg38MesVOGegpK+ohC7mbQmChSt03QbZIN2/kOloy7yWOhujwRRkFR CCeLQKTEkqtBtFH7GuBUia7xKk5p3GuDMZ4fpkq8Cfgq8GZUyXKc/Ur1p4EZrwkdsCPy 7w1A== X-Gm-Message-State: ALoCoQle+Ky5gisENTXebNpYVecINQIheDeMev4mafiynPwunrcSVcBI+xB4xW7yR4mZZ61YLyZV X-Received: by 10.182.95.40 with SMTP id dh8mr28162165obb.11.1411883452504; Sat, 27 Sep 2014 22:50:52 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.182.130.229 with SMTP id oh5ls981184obb.88.gmail; Sat, 27 Sep 2014 22:50:51 -0700 (PDT) X-Received: by 10.60.45.7 with SMTP id i7mr33044048oem.2.1411883451634; Sat, 27 Sep 2014 22:50:51 -0700 (PDT) Original-Received: from mail-ob0-x230.google.com (mail-ob0-x230.google.com [2607:f8b0:4003:c01::230]) by mx.google.com with ESMTPS id i4si14304213obh.74.2014.09.27.22.50.51 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Sat, 27 Sep 2014 22:50:51 -0700 (PDT) Received-SPF: pass (google.com: domain of gromer@google.com designates 2607:f8b0:4003:c01::230 as permitted sender) client-ip=2607:f8b0:4003:c01::230; Original-Received: by mail-ob0-f176.google.com with SMTP id vb8so2452746obc.21 for ; Sat, 27 Sep 2014 22:50:51 -0700 (PDT) X-Received: by 10.182.236.225 with SMTP id ux1mr31246982obc.57.1411883451304; Sat, 27 Sep 2014 22:50:51 -0700 (PDT) Original-Received: by 10.76.68.42 with HTTP; Sat, 27 Sep 2014 22:50:51 -0700 (PDT) Original-Received: by 10.76.68.42 with HTTP; Sat, 27 Sep 2014 22:50:51 -0700 (PDT) In-Reply-To: <54274B57.6040007@gmail.com> X-Original-Sender: gromer@google.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of gromer@google.com designates 2607:f8b0:4003:c01::230 as permitted sender) smtp.mail=gromer@google.com; dkim=pass header.i=@google.com; dmarc=pass (p=REJECT dis=NONE) header.from=google.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: , X-Original-From: Geoffrey Romer Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:13239 Archived-At: --001a11c2fad0948494050419bb1a Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Note that in the case of 'final', the presence or absence of 'virtual' makes an important semantic difference: without the 'virtual', it behaves like 'override', so you get an error if it doesn't override a virtual method in the base class. Adding 'virtual' suppresses that error, which is almost never what you want. This makes "use exactly one of the three" a pretty good rule of thumb. Le 28/09/2014 01:21, Myriachan a =C3=A9crit : > I actually wish C++ had required that overrides used the virtual > keywords. It's nice to be able to look at the class and know what is goi= ng > to behave polymorphically. override at the end would distinguish them, > sure, but then I'd have to look at the left and right side of each line > instead of just the left. > Well, actually i prefer not to mix virtual and override, because they give me different informations : - when i see virtual, i know it's the base definition - when i see override, i know it's a redefinition. If i were to mix them, i would be misled by the virtual at left, unless i checked the right part for some override... --=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 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/. --=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/. --001a11c2fad0948494050419bb1a Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable

Note that in the case of 'final', the presence or ab= sence of 'virtual' makes an important semantic difference: without = the 'virtual', it behaves like 'override', so you get an er= ror if it doesn't override a virtual method in the base class. Adding &= #39;virtual' suppresses that error, which is almost never what you want= .. This makes "use exactly one of the three" a pretty good rule of= thumb.

Le 28/09/2014 01:21, Myriacha= n a =C3=A9crit :
I actually wish C++ had required that overrides used the virtual keywords.= =C2=A0 It's nice to be able to look at the class and know what is going= to behave polymorphically.=C2=A0 override at the end would distinguish the= m, sure, but then I'd have to look at the left and right side of each l= ine instead of just the left.
Well, actually i prefer not to mix virtual and override, because they give = me different informations :
- when i see virtual, i know it's the base definition
- when i see override, i know it's a redefinition.
If i were to mix them, i would be misled by the virtual at left, unless i c= hecked the right part for some override...

--

--- You received this message because you are subscribed to the Google Grou= ps "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-proposals/.

--

---
You received this message because you are subscribed to the Google Groups &= quot;ISO C++ Standard - Future Proposals" group.
To unsubscribe from this group and stop receiving emails from it, send an e= mail to std-proposa= ls+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/<= /a>.
--001a11c2fad0948494050419bb1a-- .