220 31677 <6aa2e439-345e-4f04-8843-f38bb7b825b2@isocpp.org> article Path: news.gmane.org!.POSTED!not-for-mail From: Denis Kotov Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Simplify virtual inheritance rules Date: Sat, 18 Mar 2017 12:31:32 -0700 (PDT) Lines: 182 Approved: news@gmane.org Message-ID: <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_523_302603043.1489865492046" X-Trace: blaine.gmane.org 1489865498 7040 195.159.176.226 (18 Mar 2017 19:31:38 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sat, 18 Mar 2017 19:31:38 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBDY2PNGE6QOBBFEWW3DAKGQE6XTTC5Q@isocpp.org Sat Mar 18 20:31:33 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-pf0-f197.google.com ([209.85.192.197]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1cpK4V-0000ch-Eh for gclcip-std-proposals@m.gmane.org; Sat, 18 Mar 2017 20:31:27 +0100 Original-Received: by mail-pf0-f197.google.com with SMTP id o126sf187872209pfb.2 for ; Sat, 18 Mar 2017 12:31:33 -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: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=HTiQCId3Zwve+ChZt/aV+PT7j6X/HXaD6V4JJyQOLXg=; b=j1M3I/5YV/GP9GiYnppjbO4sN7ylLe5HO37KP4O9oKPwQP0a1jcpE2n8YkFJ/lW65r 5DBXKPNucOYYw7uQ5DrLIoWOASPrp1YpN4HxDoY7MuwGbS44YyYZeHL+FvZkg6dWJETX W7G7A5JokURFNZWV/+9AGFBr54+Xu3H/BpEyLADsAkwbHAY20HQSvroljFOlkOvWwPGO 0A72W+3PM0cNtvheUoYQf9Z+WU39gifQS8koBGlgpDKyTA4NxOPDhv4Rj59TAQHTmZZa Ix56GvNi7XjxXMGeVcH2fozy+NNtTWSi4K81/u1gCS20ehYE1K8CF9TPUJGcFSsFqUdr V+uw== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:message-id: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=HTiQCId3Zwve+ChZt/aV+PT7j6X/HXaD6V4JJyQOLXg=; b=hn3nGRs7xPlkE+COr7WHaAMr9qbEZUIhCSBkVUJFI5pCMiDEC/TACTsopZg3oaOQTU eeHA+2YU8F3s3Snptnv41b2A+TYysnyKDZfodv7zJX+kmefTIvAeQAOg2C8nF7uM91/v d/Ty9AZYZ4TllBJ+5TjE3J8WqMLn59z6aPeWwEeWGdQ4QZBCKZDuw/Fdo+AiUTaeCXn0 JMBkKaxKiGxQUoFs6WJrFV8fXH0M+MdHhjXvPMVqQyOf8jn4bfhyK1vqo8TJ5R5V23bo 4IUMybVIVzR6KgWfw821bCIk0jvzeg1sjscqbOcs4+R/+q+LTgJYY217NzEmxSW1WwVF E4Ag== 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: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=HTiQCId3Zwve+ChZt/aV+PT7j6X/HXaD6V4JJyQOLXg=; b=HupvmTsoDR801zhrpYiykPGElbCdH/D6XISZj98tFW6ZojpTc3irmHrOJrReOc2lOt 1p8NM71zCqSVRjNlHQVanOwdSsZbjFkNMdVRuBt8/ur2MUi3mAv5ucpxXzFXxc1Y6jmh YuFl5B45zL+Z/HdVMWwzkqkSPOXCli6y2Nr76LQjgw3JhfmVo6iAOXwon3wrnAzQuTFy 2NDYYaT4kWDsOpa1yXRvpqyJLl4UCVc2enmrsmsFDbWUMikEOTHj3Gn1d2qCTqM3xF+p fyfTIEk84/DnJLonJrGppFzG1J/1KjXdw9e+Mcgf72RX3l09RyXs12VAbvfshZitgBV9 t/KA== X-Gm-Message-State: AFeK/H29k6jMELND5w1JRhTw5kCZS1SC5J8npS5rOTFjKoyj829HOEsp4HUa6nTxZYDB+A== X-Received: by 10.99.113.69 with SMTP id b5mr10249208pgn.161.1489865493123; Sat, 18 Mar 2017 12:31:33 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.157.41.33 with SMTP id d30ls10927384otb.17.gmail; Sat, 18 Mar 2017 12:31:32 -0700 (PDT) X-Received: by 10.157.11.143 with SMTP id 15mr2276837oth.11.1489865492438; Sat, 18 Mar 2017 12:31:32 -0700 (PDT) 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:31677 Archived-At: ------=_Part_523_302603043.1489865492046 Content-Type: multipart/alternative; boundary="----=_Part_524_1738359098.1489865492046" ------=_Part_524_1738359098.1489865492046 Content-Type: text/plain; charset=UTF-8 Hi everyone, My proposal is to simplify virtual inheritance rules. Consider the 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 VirtualBase(str) { } }; *Proposal is the following:* *Require to specify constructor for VirtualBase 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 "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/6aa2e439-345e-4f04-8843-f38bb7b825b2%40isocpp.org. ------=_Part_524_1738359098.1489865492046 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable

Hi everyone,=


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


=



and the following code:

=C2=A0 =C2=A0 class VirtualBase
=C2=A0 =C2=A0 {
= =C2=A0 =C2=A0 public:
=C2=A0 =C2=A0 =C2=A0 =C2=A0VirtualBase(std:= :string & str)
=C2=A0 =C2=A0 =C2=A0 =C2=A0{

=C2=A0 =C2=A0 =C2=A0 =C2=A0}
=C2=A0 =C2=A0 };
<= br>
=C2=A0 =C2=A0 class Derived0 : virtual public VirtualBase
=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 : virtual = public VirtualBase
=C2=A0 =C2=A0 {
=C2=A0 =C2=A0 public= :
=C2=A0 =C2=A0 =C2=A0 =C2=A0Derived1(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 clas= s ComposedDerived
=C2=A0 =C2=A0 =C2=A0 =C2=A0: public Derived0
=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=A0= ComposedDerived(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 , D= erived1(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 };

=
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 pub= lic:
=C2=A0 =C2=A0 =C2=A0 =C2=A0ComposedDerivedDerived(std::strin= g & 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 };

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 &a= mp; 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 VirtualBase only if com= piler find more the one path of virtual inheritance like for C3 (on diagram= ) or ComposedDerived (in code) classes

--
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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/6aa2e439-345e-4f04-8843-f38bb7b825b2= %40isocpp.org.
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