220 17453 article Path: news.gmane.org!not-for-mail From: Johannes Schaub Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: In-class definition of pure virtual functions Date: Wed, 22 Apr 2015 17:49:37 +0200 Lines: 32 Approved: news@gmane.org Message-ID: References: <55377A89.7000807@gmail.com> <06dcb70f-d339-477f-9b03-38e4e57c90da@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-Trace: ger.gmane.org 1429717786 685 80.91.229.3 (22 Apr 2015 15:49:46 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 22 Apr 2015 15:49:46 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCQPNCEZSQNBBE4G36UQKGQEPL4ZCHY@isocpp.org Wed Apr 22 17:49:42 2015 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-pa0-f72.google.com ([209.85.220.72]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1YkwuD-0005we-0C for gclcip-std-proposals@m.gmane.org; Wed, 22 Apr 2015 17:49:41 +0200 Original-Received: by pacyx8 with SMTP id yx8sf421101836pac.0 for ; Wed, 22 Apr 2015 08:49:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlemail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type:x-original-sender:x-original-authentication-results :reply-to:precedence:mailing-list:list-id:list-post:list-help :list-archive:list-subscribe:list-unsubscribe; bh=iSPgcOEwBRpMv+be2OqAeoJN5ucfyfqjyXBa3lHsqF8=; b=PzITXEPPj6xffPKY+FGUY/D2NBxK6YbXSeK/OSDkhCey1BM0hjvXD4PI+2yddSk/I+ xXqulK83F+qzGsibv/BDug9p0EzCqUqJhX6w6650v2cPLdtoMFGFLUEwLxaTkXEtREs6 AGLDor+Qi/3Zw6K1WSag7VS0NFg0EbasROp4qGSEH7qwUdqO7OHjo/ivBHb4v0qZjckC oMBrKNxNDDxM23lBxfJho2Buzlv14suZxFnT0gosT7x3rtkybgxX5yR0v/JbqypziG6r 1SoLUUbhiNsZsrW0j7edC8qVC7vcEQlcl6xbXGvqwIIfEjJOxu+IwppeiREgJ39Xy9aO nbYg== 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:content-type:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:list-post:list-help:list-archive:list-subscribe :list-unsubscribe; bh=iSPgcOEwBRpMv+be2OqAeoJN5ucfyfqjyXBa3lHsqF8=; b=BnBjE8dKq51rTffzP2RmPDfCoGU/DXG7cBjQxsdDg11tvGvfILRRYg61MwgvTtDFxm bCgg4G9sVeVz+osjRSUZ7e5MolReW9tcZ9n3hAPsbUiTwbouPy2EvYaTH+Q61Ek7rTsk DSNHqEHLZkGityYi58BcC1idaCZrFxLRIaejmIwd4fKO2pMszOeiD6c7/qhXMCUjKA6o jf4Fk8Wqod8q6sVlWYjg5cgi8aqtOIWAHNyQHYnNlj/gBtDdgnOIxQCB2hqFopg6Zp9G sUL4yWkSnGu2yugsw/NBuYlhD0b6rzguvv61eKXSETcNO9munRARkAGTnS6CNFLTFQDW scbw== X-Gm-Message-State: ALoCoQkV8zQ0sCwhtIozLZZdrwJHHUVrtJAHxDOrSw40cNUifDm69yNhz60ZQ/nOozohZko7LCCJ X-Received: by 10.70.44.164 with SMTP id f4mr3254385pdm.3.1429717779847; Wed, 22 Apr 2015 08:49:39 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.107.37.72 with SMTP id l69ls584461iol.23.gmail; Wed, 22 Apr 2015 08:49:39 -0700 (PDT) X-Received: by 10.42.20.197 with SMTP id h5mr10352401icb.22.1429717779102; Wed, 22 Apr 2015 08:49:39 -0700 (PDT) Original-Received: from mail-ig0-x235.google.com (mail-ig0-x235.google.com. [2607:f8b0:4001:c05::235]) by mx.google.com with ESMTPS id f1si13790828igt.11.2015.04.22.08.49.39 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 22 Apr 2015 08:49:39 -0700 (PDT) Received-SPF: pass (google.com: domain of schaub.johannes@googlemail.com designates 2607:f8b0:4001:c05::235 as permitted sender) client-ip=2607:f8b0:4001:c05::235; Original-Received: by igblo3 with SMTP id lo3so111528igb.0 for ; Wed, 22 Apr 2015 08:49:37 -0700 (PDT) X-Received: by 10.107.133.27 with SMTP id h27mr37291374iod.31.1429717777888; Wed, 22 Apr 2015 08:49:37 -0700 (PDT) Original-Received: by 10.107.51.69 with HTTP; Wed, 22 Apr 2015 08:49:37 -0700 (PDT) In-Reply-To: X-Original-Sender: schaub.johannes@googlemail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of schaub.johannes@googlemail.com designates 2607:f8b0:4001:c05::235 as permitted sender) smtp.mail=schaub.johannes@googlemail.com; dkim=pass header.i=@googlemail.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:17453 Archived-At: 2015-04-22 17:41 GMT+02:00 Nevin Liber : > On 22 April 2015 at 10:35, Johannes Schaub > wrote: >> >> 2015-04-22 16:32 GMT+02:00 Nevin Liber : >> > On 22 April 2015 at 06:01, Columbo wrote: >> >> virtual ~MyClass() = 0 = default; >> > Why can't this particular use case (not being able to >> > instantiate the base class) be done today with protected constructors? >> >> I am not sure whether this is *the* usecase I have in mind for =0 on >> destructors. My prime usecase for it would be to make a class abstract >> without having the programmer of the derived class to write an >> implementation of the method (the compiler does it itself). > > > Again, why don't protected constructors cover this case? I'm just not > seeing it. > You still need a virtual destructor to have the class be polymorphic and allow delete through base class ptr. With the "=0" you get both with only one declaration. -- --- 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/. .