220 13504 <92d7f0ea-b21c-4645-a903-0237e3018fdb@email.android.com> article Path: news.gmane.org!not-for-mail From: George Makrydakis Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: Generalizing the equivalence of auto and template type deduction Date: Thu, 02 Oct 2014 12:43:09 +0300 Lines: 135 Approved: news@gmane.org Message-ID: <92d7f0ea-b21c-4645-a903-0237e3018fdb@email.android.com> References: <0bf78c13-6ee2-4a9a-9de5-5ce2dc0e5a66@isocpp.org> <3cc36209-3837-4b00-a976-123e01d25a72@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="----U2J4UVP8TSBB2DCAMXZZE1DUI69DPQ" Content-Transfer-Encoding: 8bit X-Trace: ger.gmane.org 1412243006 5180 80.91.229.3 (2 Oct 2014 09:43:26 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 2 Oct 2014 09:43:26 +0000 (UTC) To: std-proposals@isocpp.org,Tomasz Original-X-From: std-proposals+bncBDG4XBF6YIPBBNV4WSQQKGQEYOYX4RY@isocpp.org Thu Oct 02 11:43:19 2014 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-wi0-f200.google.com ([209.85.212.200]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1XZcut-0003W4-FK for gclcip-std-proposals@m.gmane.org; Thu, 02 Oct 2014 11:43:19 +0200 Original-Received: by mail-wi0-f200.google.com with SMTP id cc10sf937355wib.7 for ; Thu, 02 Oct 2014 02:43:19 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:user-agent:in-reply-to:references:mime-version :subject:from:date:to:message-id:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:list-post:list-help:list-archive:list-subscribe :list-unsubscribe:content-type:content-transfer-encoding; bh=aEsFUqzSl5icFy1oYsWtqG4qVGBrB7YRNUAXIcBVvQk=; b=BOc8IL1hN+d+oeELTwd9EqSCEdvh91Dk3Q3f5W0420xYxwiC3FABtC518HadFcbuSW LkhGKXqFcxlkhnn7y2RoMWsOomFn1O7cEMNR5bisDgKDtqgJFKwGtvnPSlrZqMb8MDNH kNe4Fqd8aF+caKTpRxqe5b5JcTU0Qqh4pwIPG1W2fNIhI17O966pmDh3BoinER3a0foY WSBqM190RB21pTvssd74aVXsAE7uUeHDZjj8+c5+/UfzKdgck3dGF3q+Ez1S8ABro4a1 BMQPUBDF3YEw56SCHAbcuvAacfqRNITrsj1ePKIroMdAFZrHdBa8DQIoiqrhOtrTWp7A iKj X-Gm-Message-State: ALoCoQk7+wgUiMummlTzOQpAcQek76DthKTjgx7Z1hmQ5RJKg/GQmib2p7BNqgQQsfI4X5y1qoRd X-Received: by 10.112.151.3 with SMTP id um3mr315130lbb.15.1412242999191; Thu, 02 Oct 2014 02:43:19 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.180.108.45 with SMTP id hh13ls49532wib.53.canary; Thu, 02 Oct 2014 02:43:18 -0700 (PDT) X-Received: by 10.180.100.101 with SMTP id ex5mr2493442wib.79.1412242998392; Thu, 02 Oct 2014 02:43:18 -0700 (PDT) Original-Received: from mail-wg0-x22c.google.com (mail-wg0-x22c.google.com [2a00:1450:400c:c00::22c]) by mx.google.com with ESMTPS id pj8si4815122wjb.18.2014.10.02.02.43.18 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 02 Oct 2014 02:43:18 -0700 (PDT) Received-SPF: pass (google.com: domain of irrequietus@gmail.com designates 2a00:1450:400c:c00::22c as permitted sender) client-ip=2a00:1450:400c:c00::22c; Original-Received: by mail-wg0-f44.google.com with SMTP id y10so2535051wgg.27 for ; Thu, 02 Oct 2014 02:43:18 -0700 (PDT) X-Received: by 10.180.72.239 with SMTP id g15mr2514139wiv.47.1412242998305; Thu, 02 Oct 2014 02:43:18 -0700 (PDT) Original-Received: from 178-146-131-90.mobile.cosmote.net (178-146-131-90.mobile.cosmote.net. [178.146.131.90]) by mx.google.com with ESMTPSA id iy10sm648309wic.5.2014.10.02.02.43.16 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 02 Oct 2014 02:43:17 -0700 (PDT) User-Agent: Kaiten Mail In-Reply-To: <3cc36209-3837-4b00-a976-123e01d25a72@isocpp.org> X-Original-Sender: irrequietus@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of irrequietus@gmail.com designates 2a00:1450:400c:c00::22c as permitted sender) smtp.mail=irrequietus@gmail.com; dkim=pass header.i=@gmail.com; dmarc=pass (p=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:13504 Archived-At: ------U2J4UVP8TSBB2DCAMXZZE1DUI69DPQ Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Which is what has already been said, but you ignored it. The notation gets = longer and weirder with such placeholders, not offering any real no rationa= l advantage. You are only exchanging 'typename' with auto plus decltype for= constraining even in the most trivial case. On October 2, 2014 12:29:23 PM EEST, Tomasz wrote: >Sorry, I misunderstood your point. > >I think with use of concepts as placeholders we can still require >different=20 >type. Let assume that we have concept Different Type, could >probably=20 >write: >std::pair> f =3D..; >but I would say that the programmer should specify types explicitly in >that=20 >case. > >Also for the examples were pair used in the function: We=20 >already have a longer notation that would allow us to a specify >constrained=20 >case, so there is not need to cover that in shorthand notation. > >W dniu czwartek, 2 pa=C5=BAdziernika 2014 11:13:10 UTC+2 u=C5=BCytkownik V= ille=20 >Voutilainen napisa=C5=82: >> >> On 2 October 2014 11:43, Tomasz > >wrote:=20 >> > My proposal is that every use of placholder (today we have only >auto,=20 >> but=20 >> > concept name would be a possible extension) would introduce >separate=20 >> > typename, so:=20 >> > std::pair p =3D f();=20 >> >=20 >> > Would use equivalent deduction as:=20 >> > template=20 >> > void foo(std::pair);=20 >> >> That's already how it works.=20 >> > >--=20 > >---=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 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/. --=20 ---=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. Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposa= ls/. ------U2J4UVP8TSBB2DCAMXZZE1DUI69DPQ Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable

Which is what has already been said= , but you ignored it. The notation gets longer and weirder with such placeh= olders, not offering any real no rational advantage. You are only exchangin= g 'typename' with auto plus decltype for constraining even in the most triv= ial case.



On October 2, 2014 12:29:23 PM EEST, Tom= asz <tomaszkam@gmail.com> wrote:
Sorry, I misunderstood your point.

I think with= use of concepts as placeholders we can still require different type. Let a= ssume that we have concept Different Type<A,B>, could probably write:=
std::pair<auto{T}, Different Type<T>> f =3D..;
but I= would say that the programmer should specify types explicitly in that case= ..

Also for the examples were pair<auto, auto> used in the = function: We already have a longer notation that would allow us to a specif= y constrained case, so there is not need to cover that in shorthand notatio= n.

W dniu czwartek, 2 pa=C5=BAdziernika 2014 11:13:10 UTC+2 u=C5= =BCytkownik Ville Voutilainen napisa=C5=82:
On 2 October 2014 11:43, Tomasz <toma...@gmail.com>= ; wrote:
> My proposal is that every use of placholder (today we have only = auto, but
> concept name would be a possible extension) would introduce sepa= rate
> typename, so:
> std::pair<auto, auto> p =3D f();
>
> Would use equivalent deduction as:
> template<typename T1, typename T2>
> void foo(std::pair<T1, T2>);

That's already how it works.

--

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