220 31218 <40492ec6-e04a-4db0-a72d-243c4ca9896e@isocpp.org> article Path: news.gmane.org!.POSTED!not-for-mail From: Denis Kotov Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Removing forward references ("universal" references) from the standard Date: Tue, 28 Feb 2017 13:24:49 -0800 (PST) Lines: 156 Approved: news@gmane.org Message-ID: <40492ec6-e04a-4db0-a72d-243c4ca9896e@isocpp.org> References: <69c0683c-3b36-4de4-941d-9487366615d6@isocpp.org> <77fd5ab0-76dc-47d5-b0cc-cd7f0a32f921@isocpp.org> <24056019-259b-49cd-b868-871738502e24@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_880_1560263533.1488317089160" X-Trace: blaine.gmane.org 1488317092 26114 195.159.176.226 (28 Feb 2017 21:24:52 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Tue, 28 Feb 2017 21:24:52 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBDY2PNGE6QOBBIOV27CQKGQEUNZUQZA@isocpp.org Tue Feb 28 22:24:47 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 1cipGG-000614-SJ for gclcip-std-proposals@m.gmane.org; Tue, 28 Feb 2017 22:24:45 +0100 Original-Received: by mail-yw0-f198.google.com with SMTP id 2sf41424245ywn.1 for ; Tue, 28 Feb 2017 13:24:51 -0800 (PST) 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=/dpcCNnjr/0wU/ClfIuVRCO1WeFZJ6D8vmJAIzmYR08=; b=UhKqKZ49IeNYRuzKDqiqveQVK0qX4qEunPou2Kkoxkt7YWmeaajO8gpVX2LwCZdi7E QyhEXdwHpZoA0/JPZ2tgQQDCSkPqOgBS+ew2lRb/5HHRITXY3NKilWOCe2z7AB4RMg3U kz4z2U1/AVAX8DGhYhuWTpU8/NAQoK7CYZr/IX52g2IYTDm70BkitBWMYNlSMBitrV5N 9vN64hB6VFJA45gqWlwpSDA9AEkncpm6D9aVP6RNG77+NGJqu3nSIcEKXMc8toTko6GU 8Agn4TKUdOBdmTNxvwjBPSQ+i+4L09RWTMNcqsgqGeOjtRjrklG6M9VSx9pUIOVVWQzu BQIQ== 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=/dpcCNnjr/0wU/ClfIuVRCO1WeFZJ6D8vmJAIzmYR08=; b=KThH+0YYlMQBgMXAsdQT5aQki61JRyXVCNkiDC3btns11tE+VLsh8ne2dDwyT2HuAT Gcy6bYUuSqQ8R1vl/kB+CE71c+cjc0sQv8AE9Q16VegcWXVD7xawl8EmvvAN1kjIDnR0 CEgPj87O3w/FNx90tlEvDadvcKlkBkPzCdyrEQt1qMri+dGKFdiUF/to2wMGe8QZMZ8f HicjJspn4HEpamrWRufHpgC9SBSIy1+8rvdMGSijC8Efqlmyic7EbgdFYaCbVCQby3cs 3YJ+X0tvxAFTROdh35/B4jfre2V3R4uGv/uyqJ34euQrFZvZWVyngy9ZjojLCnPwqcsd vQkg== 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=/dpcCNnjr/0wU/ClfIuVRCO1WeFZJ6D8vmJAIzmYR08=; b=Oy2irVXKqgeQo821Dr7dn1HY++nM1D9U6jsmwm5h3fhTZpf2whr4KRYOTF0iFVOviL s/XmiT37vCtRaGWD2bkyXjcVdpeXklBbzzoqDzv+qM8FkrTijiLWddlkFV2g4qWZlJtW gKvUL/Y7g8//oGir0bi+5ztqW2ojuSjhT05QvK7807vKA3aZFZ+L6iARSKkhNFG9bZ56 Ua5uwLr3OyOzd/lyOP4eIkJxDRV/IzmyMMNMGLJqHau9lvDofN9L8GxYaXco8wexyqyG 05Eg9Q1Zv79+h/4pY1OI4rUI9qRoaOJd39sgbkOHc90T7Jz7Ccl1fQi8GXMDKRtLxqDw B2sQ== X-Gm-Message-State: AMke39lAfxnUZBN1jtxxKv/wEh/IVMndiXmYGuY98UqtQ7I6Cg/Ia+rBNHuy5pwmZEAmYw== X-Received: by 10.129.65.11 with SMTP id o11mr1546215ywa.131.1488317090657; Tue, 28 Feb 2017 13:24:50 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.157.3.54 with SMTP id 51ls351517otv.20.gmail; Tue, 28 Feb 2017 13:24:49 -0800 (PST) X-Received: by 10.157.7.4 with SMTP id 4mr547023ote.13.1488317089758; Tue, 28 Feb 2017 13:24:49 -0800 (PST) In-Reply-To: <24056019-259b-49cd-b868-871738502e24@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:31218 Archived-At: ------=_Part_880_1560263533.1488317089160 Content-Type: multipart/alternative; boundary="----=_Part_881_535413334.1488317089160" ------=_Part_881_535413334.1488317089160 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Hi TONGARI J, Thanks for very useful example !!!! Your solution fixes the issue very elegantly and at the same case we have= =20 extensible function that can take all available arguments. Maybe I was a bit wrong. =D0=B2=D1=82=D0=BE=D1=80=D0=BD=D0=B8=D0=BA, 28 =D1=84=D0=B5=D0=B2=D1=80=D0= =B0=D0=BB=D1=8F 2017 =D0=B3., 9:38:25 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 TONGARI J =D0=BD=D0=B0=D0=BF=D0= =B8=D1=81=D0=B0=D0=BB: > > Hi Denis, > > I believe the solution below serves your need well. > template::value, bool> = =3D=20 > true> > using rval =3D T; > > template > void f(rval&&) > { > std::cout << "rvalue_reference\n"; > } > > template > void f(T&) > { > std::cout << "lvalue_reference\n"; > } > Live demo: http://melpon.org/wandbox/permlink/1SvJVZ8OdFET2qPb > > You can use rval when you want to ensure T is a value type, not a=20 > reference thing. > --=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/40492ec6-e04a-4db0-a72d-243c4ca9896e%40isocpp.or= g. ------=_Part_881_535413334.1488317089160 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Hi=C2=A0TONGARI J,

Thanks for very useful example !!!!
= Your solution fixes the issue very ele= gantly and at the same case we have extensible function that can take all a= vailable arguments.

Maybe I was= a bit wrong.

=D0=B2=D1=82=D0=BE=D1=80=D0=BD=D0=B8=D0= =BA, 28 =D1=84=D0=B5=D0=B2=D1=80=D0=B0=D0=BB=D1=8F 2017 =D0=B3., 9:38:25 UT= C+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 TONGARI J =D0=BD=D0=B0=D0=BF=D0=B8=D1=81=D0=B0=D0=BB:
Hi Denis,

I= believe the solution below serves your need well.
template<class T, std::enable_if_t<!std::is_referenc= e<T<= /span>>::va= lue, bool><= /span> =3D true>
using rval <= /span>=3D T;

<= /span>template= <class T>
void f(rv= al<T= >&&)
{
=C2=A0 =C2=A0 std::cout << "rvalue= _reference\n";
}

template<class T>
void f(T&)
{
=C2=A0 =C2=A0 std::cout <= < &q= uot;lvalue_reference\n";
}
<= /code>

You can use=C2=A0rval<T>=C2=A0when you want to ensure T is a value type, not a r= eference thing.

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