220 31678 article Path: news.gmane.org!.POSTED!not-for-mail From: Ville Voutilainen Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Simplify virtual inheritance rules Date: Sat, 18 Mar 2017 21:45:02 +0200 Lines: 85 Approved: news@gmane.org Message-ID: 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/alternative; boundary=001a113cd862c0a7a1054b068711 X-Trace: blaine.gmane.org 1489866303 18811 195.159.176.226 (18 Mar 2017 19:45:03 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sat, 18 Mar 2017 19:45:03 +0000 (UTC) To: "ISO C++ Standard - Future Proposals" Original-X-From: std-proposals+bncBC5JHI7A7ALRBP44W3DAKGQEFOGKGDY@isocpp.org Sat Mar 18 20:44:59 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-yw0-f198.google.com ([209.85.161.198]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1cpKHa-0004JJ-Sk for gclcip-std-proposals@m.gmane.org; Sat, 18 Mar 2017 20:44:59 +0100 Original-Received: by mail-yw0-f198.google.com with SMTP id u138sf317048298ywg.0 for ; Sat, 18 Mar 2017 12:45:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :x-original-sender:x-original-authentication-results:reply-to :precedence:mailing-list:list-id:x-spam-checked-in-group:list-post :list-help:list-archive:list-subscribe:list-unsubscribe; bh=9XNP3NoXXEuhtoZRuHTyvGR7yaQonoUjV3UPnFXKZSc=; b=iQakb1FXvXm1MLwVCrLXDb4GPWm6Cg6wBJeVP9Nk6CBq0PVLPe2T1PLv1+TmlgbCpG 8KGmf8WPyvWdad3dea4R/LhG9jbJ723aAKDXnqvcTjcCBDDUSZoxj7yermYoBnDlYyYW b+jBH9OfXXw7QRfs1gDephO7ft6xCO5rXhN9Jx90Vm406iXeglUQnVae1lDlcJBgjLV6 yKFIwLpLb4LO/7RzV+W96LGfwSMRN0U/0U38TAnJC6OUA1ZFxmAIOyIf6QmosYQzvxDq JRpXTwKbk2L3Ec556vtGjqzvpLVV4lDD5I3GqIo+tcQqJTWu2LLo3k2DPjvXdny3IZdl Hp9A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=9XNP3NoXXEuhtoZRuHTyvGR7yaQonoUjV3UPnFXKZSc=; b=Mq7RGPgDUs6dR1d3IbSCZ4gQ0GmmgDtB/bM+u8zLKai5daMnK1lO5uxONwc+w8cE6j ElkQcd7aOUeXXua+ZjxKA2rkoIusSWoSgGJxo7LKVkDHIXxWvoclCRIEDPoToGRcu7jw jGyD53LBVwpMc5M81PoDKozchS02XzuKvOViuf5OXCru+NR6mSJacfy4cZgnpjVyfLM2 jW44F8P/mFvwt6ZnkbafOynyEXhovCP7NjmFZcScmPbvsIDyy7VWdC0E2wp1ZKyXXgQO jfvXE2XxuBzZiFI4ETrTffxWtP6WATXvAxIFRlAAZl76A+oixrDHJfGIKotv0Z3boZ3I Ukcw== X-Gm-Message-State: AFeK/H3VnSfqCwbXSK+ARYFUgIrz/bDZ3B4bF/orFja6Ra6XEPwHD0n6Mpo1VDeGu2TNIQ== X-Received: by 10.129.87.15 with SMTP id l15mr2416039ywb.0.1489866304597; Sat, 18 Mar 2017 12:45:04 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.157.89.216 with SMTP id u24ls4682975otg.40.gmail; Sat, 18 Mar 2017 12:45:03 -0700 (PDT) X-Received: by 10.157.54.210 with SMTP id s18mr12267605otd.245.1489866303801; Sat, 18 Mar 2017 12:45:03 -0700 (PDT) Original-Received: from mail-oi0-x22f.google.com (mail-oi0-x22f.google.com. [2607:f8b0:4003:c06::22f]) by mx.google.com with ESMTPS id f141si1816986oih.3.2017.03.18.12.45.03 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 18 Mar 2017 12:45:03 -0700 (PDT) Received-SPF: pass (google.com: domain of ville.voutilainen@gmail.com designates 2607:f8b0:4003:c06::22f as permitted sender) client-ip=2607:f8b0:4003:c06::22f; Original-Received: by mail-oi0-x22f.google.com with SMTP id w81so8436229oig.1 for ; Sat, 18 Mar 2017 12:45:03 -0700 (PDT) X-Received: by 10.202.54.4 with SMTP id d4mr11596529oia.45.1489866302988; Sat, 18 Mar 2017 12:45:02 -0700 (PDT) Original-Received: by 10.157.13.22 with HTTP; Sat, 18 Mar 2017 12:45:02 -0700 (PDT) In-Reply-To: <6aa2e439-345e-4f04-8843-f38bb7b825b2@isocpp.org> X-Original-Sender: ville.voutilainen@gmail.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com; spf=pass (google.com: domain of ville.voutilainen@gmail.com designates 2607:f8b0:4003:c06::22f as permitted sender) smtp.mailfrom=ville.voutilainen@gmail.com; dmarc=pass (p=NONE sp=NONE 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:31678 Archived-At: --001a113cd862c0a7a1054b068711 Content-Type: text/plain; charset=UTF-8 On 18 March 2017 at 21:31, Denis Kotov wrote: > 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* > ComposedDerivedDerived didn't initialize ComposedDerived in your original code or this modified code. Also, there's no reason that a compiler could find an initialization for a virtual base, since that initialization may be in a separate translation unit that the compiler doesn't see, so this idea doesn't work at all. -- 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/CAFk2RUZgeRfv4zYnc%2By_Cw1-1onyj-725pq-UUizv8GVm8KQCQ%40mail.gmail.com. --001a113cd862c0a7a1054b068711 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable


On 18 March 2017 at 21:31, Denis Kotov <redradist@gmail.com><= /span> wrote:
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 };
<= /div>

Proposal is the following:
=C2=A0 =C2=A0Requ= ire to specify constructor for VirtualBase only if compiler find more the o= ne path of virtual inheritance like for C3 (on diagram) or ComposedDerived = (in code) classes


Compo= sedDerivedDerived didn't initialize ComposedDerived in your original co= de or this modified code. Also, there's no reason that
a = compiler could find an initialization for a virtual base, since that initia= lization may be in a separate translation unit that the compiler doesn'= t
see, so this idea doesn't work at all.
<= br>

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