220 31694 <1b33375c-526b-4e20-a691-a85d512fa4a8@isocpp.org> article Path: news.gmane.org!.POSTED!not-for-mail From: Denis Kotov Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Simplify virtual inheritance rules Date: Sun, 19 Mar 2017 06:07:04 -0700 (PDT) Lines: 221 Approved: news@gmane.org Message-ID: <1b33375c-526b-4e20-a691-a85d512fa4a8@isocpp.org> References: <6aa2e439-345e-4f04-8843-f38bb7b825b2@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_713_2045404918.1489928824934" X-Trace: blaine.gmane.org 1489928830 28561 195.159.176.226 (19 Mar 2017 13:07:10 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sun, 19 Mar 2017 13:07:10 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBDY2PNGE6QOBB6MEXLDAKGQERF4JQMA@isocpp.org Sun Mar 19 14:07:05 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-it0-f71.google.com ([209.85.214.71]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1cpaY0-0006TA-J8 for gclcip-std-proposals@m.gmane.org; Sun, 19 Mar 2017 14:07:00 +0100 Original-Received: by mail-it0-f71.google.com with SMTP id r141sf95506970ita.6 for ; Sun, 19 Mar 2017 06:07:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:message-id:in-reply-to:references:subject:mime-version :x-original-sender:reply-to:precedence:mailing-list:list-id :x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=Os2baB5RjxpvLkV3WKmM+YlneeIioxxh7k44/U8fTGs=; b=RxHS7GgK7Muyl8wkY4I9onpHF2hGLAlTEMW7CxOEW2m//82T3wGzocGS467+px3Q4q j8jP2qNaWcePQHVFzjfdjM6pJTqcyDK9oCCN58ZNWThcp4p4fMfqxhKAsRmuozI8cnbv ygImANE5PJA4ITNVIvmN329a4xYxVGBztsAc/JqfoYYY2wib9ks1mk/hVjI2mEdtOjQO n/Hhlw3zOPX3dRtwWqXby2rHd+deo7hgZJI0sFF+XZpm2/OKAPTWTj9GDN2Nb7XamNzq pqc6NBHlr2XOgVYE0C8d11TukpvsxTYwcMT0Hnx0D1Xr6mZR0q4ZhcAvjUZQZycSc8Gy uICQ== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:message-id:in-reply-to:references:subject:mime-version :x-original-sender:reply-to:precedence:mailing-list:list-id :x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=Os2baB5RjxpvLkV3WKmM+YlneeIioxxh7k44/U8fTGs=; b=E5LBP39Dt4DOCS1uIaE6cM9tmc6eS16JP+J5KHvrhjs+JBI+O71KCK3Pd9zQtpRtq+ /DjSF8GiUk2Uxd1v4WzyDZ3wl2U6y1vK5RvQVUkYeRT/lWdiw8OJARuNkHcwdNHKye72 KT7bnSo76zimOJTYnA/0sJz/cvt3ZEzpjoUt7UL1lyHNZXlo52v55oFUgj3/+d3N4oxx sL5zo9aXDowO3Qoe9wraPTWfzinBAmJeG9BzVu/7EsM0WXLAoKmZQ7nZDk2WtPxl7yUM 9Ztu/l/yEUj/cGxlwKpajYQHxoAOwYn/tFrsjV6WcNtMvysF7GVa41Ilx7wIrSR+aJl/ 6VrQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:message-id:in-reply-to:references :subject:mime-version:x-original-sender:reply-to:precedence :mailing-list:list-id:x-spam-checked-in-group:list-post:list-help :list-archive:list-subscribe:list-unsubscribe; bh=Os2baB5RjxpvLkV3WKmM+YlneeIioxxh7k44/U8fTGs=; b=qB4OkjdX870HWhQMO3s+jNB2ba+9cSh2UWHLki5d+UAgBBsaV4k0DhPy8HkD0UACHF EUDjXEjLCEhdvsBQkJvnIYoepw62NMljgIHihXtTf2CvwYQOubtlEK/pYSvb3RPth85P bicoU+db/g+V1ZXaSAeDwrPDqdDaqyONhcY7kdDPtA6QqzgZCYuNAQjoKZ5xjmFCvJF1 Y10hTOigTuQBuFxJrp17EhEDkVC5h5N9B+mJaaszR+fuJscvKDgxnHl9SSAwIDq7kyLK EFoBr0frznJaNjHmRIaHKlNx1lz4OFIMIhgV/kMEBPcujB+QwbEQ/nMe9wElRL3T6Tqc CyAw== X-Gm-Message-State: AFeK/H0Js8NN7XvFe/THkngYRO4pzEXqtV6zEuL1g6t+/3LcmujDdIgbucn9ujhBa6ZxZg== X-Received: by 10.36.89.138 with SMTP id p132mr205113itb.24.1489928826133; Sun, 19 Mar 2017 06:07:06 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.157.2.98 with SMTP id 89ls8775526otb.22.gmail; Sun, 19 Mar 2017 06:07:05 -0700 (PDT) X-Received: by 10.157.61.131 with SMTP id l3mr2397635otc.1.1489928825318; Sun, 19 Mar 2017 06:07:05 -0700 (PDT) In-Reply-To: <6aa2e439-345e-4f04-8843-f38bb7b825b2@isocpp.org> X-Original-Sender: redradist@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:31694 Archived-At: ------=_Part_713_2045404918.1489928824934 Content-Type: multipart/alternative; boundary="----=_Part_714_1735362021.1489928824934" ------=_Part_714_1735362021.1489928824934 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable To share my view more clear I have added a new picture: =D1=81=D1=83=D0=B1=D0=B1=D0=BE=D1=82=D0=B0, 18 =D0=BC=D0=B0=D1=80=D1=82=D0= =B0 2017 =D0=B3., 21:31:32 UTC+2 =D0=BF=D0=BE=D0=BB=D1=8C=D0=B7=D0=BE=D0=B2= =D0=B0=D1=82=D0=B5=D0=BB=D1=8C Denis Kotov =D0=BD=D0=B0=D0=BF=D0=B8=D1=81= =D0=B0=D0=BB: > > Hi everyone, > > > My proposal is to simplify virtual inheritance rules. Consider the=20 > following class hierarchy: > > > > > > and the following code: > > class VirtualBase > { > public: > VirtualBase(std::string & str) > { > > } > }; > > class Derived0 : virtual public VirtualBase > { > public: > Derived0(std::string & str) > : VirtualBase(str) > { > > } > }; > > class Derived1 : virtual public VirtualBase > { > public: > Derived1(std::string & str) > : VirtualBase(str) > { > > } > }; > > class ComposedDerived > : public Derived0 > , public Derived1 > { > public: > ComposedDerived(std::string & str) > : Derived0(str) > , Derived1(str) > , VirtualBase(str) > { > > } > }; > > Let's inherit from ComposedDerived again: > > class ComposedDerivedDerived > : public ComposedDerived > , public NewClass > { > public: > ComposedDerivedDerived(std::string & str) > : VirtualBase(str) > { > > } > }; > > I want to simplify it like the following: > > class ComposedDerivedDerived > : public ComposedDerived > , public NewClass > { > public: > ComposedDerivedDerived(std::string & str) // Here is no=20 > VirtualBase(str) > { > > } > }; > > *Proposal is the following:* > *Require to specify constructor for VirtualBase only if compiler find= =20 > more the one path of virtual inheritance like for C3 (on diagram) or=20 > ComposedDerived (in code) classes* > --=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. To view this discussion on the web visit https://groups.google.com/a/isocpp= ..org/d/msgid/std-proposals/1b33375c-526b-4e20-a691-a85d512fa4a8%40isocpp.or= g. ------=_Part_714_1735362021.1489928824934 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
To share my view more clear I have added a new picture:



=D1=81=D1=83=D0=B1=D0=B1=D0= =BE=D1=82=D0=B0, 18 =D0=BC=D0=B0=D1=80=D1=82=D0=B0 2017 =D0=B3., 21:31:32 U= TC+2 =D0=BF=D0=BE=D0=BB=D1=8C=D0=B7=D0=BE=D0=B2=D0=B0=D1=82=D0=B5=D0=BB=D1= =8C Denis Kotov =D0=BD=D0=B0=D0=BF=D0=B8=D1=81=D0=B0=D0=BB:

Hi ev= eryone,


My propo= sal is to simplify virtual inheritance rules. Consider the following class = hierarchy:




and the following code:

<= /div>
=C2=A0 =C2=A0 class VirtualBase
=C2=A0 =C2=A0 {
=C2=A0 =C2=A0 public:
=C2=A0 =C2=A0 =C2=A0 =C2=A0VirtualB= ase(std::string & str)
=C2=A0 =C2=A0 =C2=A0 =C2=A0{

=C2=A0 =C2=A0 =C2=A0 =C2=A0}
=C2=A0 =C2=A0 };

=C2=A0 =C2=A0 class Derived0 : virtual public Virtual= Base
=C2=A0 =C2=A0 {
=C2=A0 =C2=A0 public:
= =C2=A0 =C2=A0 =C2=A0 =C2=A0Derived0(std::string & str)
=C2=A0= =C2=A0 =C2=A0 =C2=A0 =C2=A0 : VirtualBase(str)
=C2=A0 =C2=A0 =C2= =A0 =C2=A0{

=C2=A0 =C2=A0 =C2=A0 =C2=A0}
=C2=A0 =C2=A0 };

=C2=A0 =C2=A0 class Derived1 : v= irtual public VirtualBase
=C2=A0 =C2=A0 {
=C2=A0 =C2=A0= public:
=C2=A0 =C2=A0 =C2=A0 =C2=A0Derived1(std::string & st= r)
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 : VirtualBase(str)
=C2=A0 =C2=A0 =C2=A0 =C2=A0{

=C2=A0 =C2=A0 =C2= =A0 =C2=A0}
=C2=A0 =C2=A0 };

=C2=A0 =C2= =A0 class ComposedDerived
=C2=A0 =C2=A0 =C2=A0 =C2=A0: public Der= ived0
=C2=A0 =C2=A0 =C2=A0 =C2=A0, public Derived1
=C2= =A0 =C2=A0 {
=C2=A0 =C2=A0 public:
=C2=A0 =C2=A0 =C2=A0= =C2=A0ComposedDerived(std::string & str)
=C2=A0 =C2=A0 =C2= =A0 =C2=A0 =C2=A0 : Derived0(str)
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2= =A0 , Derived1(str)
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 , VirtualB= ase(str)
=C2=A0 =C2=A0 =C2=A0 =C2=A0{

= =C2=A0 =C2=A0 =C2=A0 =C2=A0}
=C2=A0 =C2=A0 };
Let's inherit from ComposedDerived again:

=C2=A0 =C2=A0 class ComposedDerivedDerived
=C2=A0 = =C2=A0 =C2=A0 =C2=A0: public ComposedDerived
=C2=A0 =C2=A0 =C2=A0= =C2=A0, public NewClass
=C2=A0 =C2=A0 {
=C2=A0 =C2= =A0 public:
=C2=A0 =C2=A0 =C2=A0 =C2=A0ComposedDerivedDerived(std= ::string & str)
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0: Virt= ualBase(str)
=C2=A0 =C2=A0 =C2=A0 =C2=A0{

=C2=A0 =C2=A0 =C2=A0 =C2=A0}
=C2=A0 =C2=A0 };

I want to simplify it like the following:
=
=C2=A0 =C2=A0 class ComposedDerivedDerived
= =C2=A0 =C2=A0 =C2=A0 =C2=A0: public ComposedDerived
=C2=A0 =C2=A0= =C2=A0 =C2=A0, public NewClass
=C2=A0 =C2=A0 {
=C2=A0 = =C2=A0 public:
=C2=A0 =C2=A0 =C2=A0 =C2=A0ComposedDerivedDerived(= std::string & str) // Here is no VirtualBase(str)
=C2=A0= =C2=A0 =C2=A0 =C2=A0{

=C2=A0 =C2=A0 =C2=A0 =C2=A0= }
=C2=A0 =C2=A0 };

Proposal is the following:
=C2=A0 =C2=A0Require to specify constructor for VirtualBa= se only if compiler find more the one path of virtual inheritance like for = C3 (on diagram) or ComposedDerived (in code) classes

--
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.
To view this discussion on the web visit https://groups.google.= com/a/isocpp.org/d/msgid/std-proposals/1b33375c-526b-4e20-a691-a85d512fa4a8= %40isocpp.org.
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