220 7491 article Path: news.gmane.org!not-for-mail From: Ville Voutilainen Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: noexcept(auto) Date: Sat, 26 Oct 2013 23:58:17 +0300 Lines: 152 Approved: news@gmane.org Message-ID: References: <40170c6f-b3f1-4368-aac8-300b9b8dbe44@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary=047d7bdc9c524ade4104e9ab20df X-Trace: ger.gmane.org 1382821095 9726 80.91.229.3 (26 Oct 2013 20:58:15 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sat, 26 Oct 2013 20:58:15 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBC5JHI7A7ALRB2OZWCJQKGQEW6UXLKY@isocpp.org Sat Oct 26 22:58:21 2013 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ob0-f199.google.com ([209.85.214.199]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1VaAw8-0007KI-R8 for gclcip-std-proposals@m.gmane.org; Sat, 26 Oct 2013 22:58:21 +0200 Original-Received: by mail-ob0-f199.google.com with SMTP id gq1sf8123422obb.2 for ; Sat, 26 Oct 2013 13:58:19 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:date :message-id:subject:from:to: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; bh=AYKygSNB19pXGfpR+N4mzrNqQRnwnUCI2vhlaV8Dscw=; b=QX4YmCRsL535ouRwDavh64wGfsX+SrK0AC9H0YqgZ/HMjqUmL2t7oPFWjZSEpl1WAa uaXUYbrgMIqvH3EsA1URYE0L9ISUkvqNRY+uITmiO867nYv/qANNirhtxAGUCbdDQkml TUwrZG6NSRkyuWXDezyHDRjl9VpgWjTlowEbaNNiivp3ZVkaWFQmyoycF49iDfkIC/D5 CWgMe/OIiCx+wdb67INi+LF10qPnJL29fiB/HczGRRXKce2NHik7kgYjV+ntP6mentlC nowNCLm3I0F4WtT3siadwIzw0oDfQyZudqWNojh0oCAZQivOTHIE/VWfRM6bXeQsHnPh hzfQ== X-Gm-Message-State: ALoCoQlED0QHIYflDTEcI1fiTK0jPrw2g5HgyZxMjnqrcyHp0Gw83n0s/4gBkd08ov+iHpLzbRd4 X-Received: by 10.50.17.101 with SMTP id n5mr1935352igd.2.1382821099576; Sat, 26 Oct 2013 13:58:19 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.49.129.8 with SMTP id ns8ls1547853qeb.39.gmail; Sat, 26 Oct 2013 13:58:17 -0700 (PDT) X-Received: by 10.224.24.201 with SMTP id w9mr19973319qab.103.1382821097536; Sat, 26 Oct 2013 13:58:17 -0700 (PDT) Original-Received: from mail-qe0-x234.google.com (mail-qe0-x234.google.com [2607:f8b0:400d:c02::234]) by mx.google.com with ESMTPS id 7si6287366qeh.148.2013.10.26.13.58.17 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Sat, 26 Oct 2013 13:58:17 -0700 (PDT) Received-SPF: pass (google.com: domain of ville.voutilainen@gmail.com designates 2607:f8b0:400d:c02::234 as permitted sender) client-ip=2607:f8b0:400d:c02::234; Original-Received: by mail-qe0-f52.google.com with SMTP id w7so3193638qeb.11 for ; Sat, 26 Oct 2013 13:58:17 -0700 (PDT) X-Received: by 10.49.5.231 with SMTP id v7mr19277722qev.58.1382821097297; Sat, 26 Oct 2013 13:58:17 -0700 (PDT) Original-Received: by 10.224.11.197 with HTTP; Sat, 26 Oct 2013 13:58:17 -0700 (PDT) In-Reply-To: X-Original-Sender: ville.voutilainen@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of ville.voutilainen@gmail.com designates 2607:f8b0:400d:c02::234 as permitted sender) smtp.mail=ville.voutilainen@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:7491 Archived-At: --047d7bdc9c524ade4104e9ab20df Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On 26 October 2013 23:18, Daniel Kr=FCgler wrot= e: > 2013/10/26 Daryle Walker : > > [This sometimes pops up on other threads, but now with a thread of its > own, > > it's searchable for the next person who wants to discuss it.] > > > > I think there's going to be a "decltype(auto)" in an upcoming standard. > Use > > that text in place of a function return type, and the compiler will fil= l > in > > that type with whatever the function actually returns. It requires that > the > > first declaration of the function is the actual definition, since its > pure > > declaration would never be complete and therefore couldn't be used like > > other function pure-declarations. > > > > The "noexcept(auto)" construct works in a similar fashion. When > declaring a > > function, and that first declaration is also the definition, you can us= e > > "auto" as the expression inside the noexcept clause. And then the > compiler > > will compute the noexcept status of the function's internal code and us= e > > that result as the function's noexcept status. It'll probably be used i= n > > short functions that already use decltype(auto). > > > > Has this second construct already been proposed? > > Do you mean a second time? > > http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2010/n3207.htm > Or a third time, since noexcept(auto) was requested by the NB comment FI 5 for C++14. That NB comment was rejected, so we'll likely try again for C++17. > > That being said I believe that its worth to reconsider that now, > hopefully we have now experience enough to give some good answers to > the problems mentioned in the proposal. At the time where the original > proposal had been made (and was rejected) the C++11 standard was > supposed to be finished. > > > Most of the problems in the proposal aren't much different from potential problems that arise when deducing a function return type, I think. --=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/. --047d7bdc9c524ade4104e9ab20df Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable



On 26 October 2013 23:18, Daniel Kr=FCgler <daniel.kruegle= r@gmail.com> wrote:
2013/10/26 Daryle Walker <darylew@gmail.com>:
> [This sometimes pops up on other threads, but now wi= th a thread of its own,
> it's searchable for the next person who wants to discuss it.]
>
> I think there's going to be a "decltype(auto)" in an upc= oming standard. Use
> that text in place of a function return type, and the compiler will fi= ll in
> that type with whatever the function actually returns. It requires tha= t the
> first declaration of the function is the actual definition, since its = pure
> declaration would never be complete and therefore couldn't be used= like
> other function pure-declarations.
>
> The "noexcept(auto)" construct works in a similar fashion. W= hen declaring a
> function, and that first declaration is also the definition, you can u= se
> "auto" as the expression inside the noexcept clause. And the= n the compiler
> will compute the noexcept status of the function's internal code a= nd use
> that result as the function's noexcept status. It'll probably = be used in
> short functions that already use decltype(auto).
>
> Has this second construct already been proposed?

Do you mean a second time?

http://www.open-std.org/jtc1/sc22/wg21/docs/papers/201= 0/n3207.htm

Or a third time, since = noexcept(auto) was requested by the NB comment
FI 5 for C++14. That NB comment was rejected, so we'll likel= y try again for
C++17.
=A0

That being said I believe that its worth to reconsider that now,
hopefully we have now experience enough to give some good answers to
the problems mentioned in the proposal. At the time where the original
proposal had been made (and was rejected) the C++11 standard was
supposed to be finished.



Most of the problems in the proposal aren't = much different from potential problems
that arise when deduci= ng a function return type, I think.=A0

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