220 41587 <42fc876e-a4c7-a247-bc7f-632efbe1b28d@gmail.com> article Path: news.gmane.org!.POSTED.blaine.gmane.org!not-for-mail From: Matthew Woehlke Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: A virtual method that must *always* be overridden? Date: Thu, 4 Apr 2019 13:18:52 -0400 Approved: news@gmane.org Message-ID: <42fc876e-a4c7-a247-bc7f-632efbe1b28d@gmail.com> Reply-To: std-proposals@isocpp.org Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Injection-Info: blaine.gmane.org; posting-host="blaine.gmane.org:195.159.176.226"; logging-data="46231"; mail-complaints-to="usenet@blaine.gmane.org" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.0 To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBC37LBFWUIFBB77YTDSQKGQE7YSARWQ@isocpp.org Thu Apr 04 19:18:57 2019 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-qt1-f200.google.com ([209.85.160.200]) by blaine.gmane.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.89) (envelope-from ) id 1hC60v-000BmN-8e for gclcip-std-proposals@m.gmane.org; Thu, 04 Apr 2019 19:18:57 +0200 Original-Received: by mail-qt1-f200.google.com with SMTP id t22sf2891069qtc.13 for ; 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[66.194.253.20]) by smtp.googlemail.com with ESMTPSA id g34sm13316827qtc.9.2019.04.04.10.18.52 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 04 Apr 2019 10:18:52 -0700 (PDT) Openpgp: preference=signencrypt Content-Language: en-US X-Original-Sender: mwoehlke.floss@gmail.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=tbxMO9AD; spf=pass (google.com: domain of mwoehlke.floss@gmail.com designates 209.85.220.41 as permitted sender) smtp.mailfrom=mwoehlke.floss@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-Google-Group-Id: 399137483710 List-Post: , List-Help: , List-Archive: List-Subscribe: , List-Unsubscribe: , Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:41587 Archived-At: While adding a `virtual Self* clone() = 0` to a class yesterday, I realized something... why does C++ not have a way to mark a method that must *always* be overridden? I'm talking about something *more* than a pure virtual, i.e.: struct Root { virtual Root* foo() bikeshed; }; struct Derived : Root { }; struct MoreDerived : Derived { virtual Root* foo(); }; Root x; // okay Derived y; // error: 'foo' was not overridden MoreDerived z; // okay Would this be useful? -- Matthew -- 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/42fc876e-a4c7-a247-bc7f-632efbe1b28d%40gmail.com. .