220 11828 article Path: news.gmane.org!not-for-mail From: Ville Voutilainen Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: N4115, N3728: std::tuple as metadata Date: Fri, 11 Jul 2014 10:29:11 +0300 Lines: 29 Approved: news@gmane.org Message-ID: References: <6598852E-AFEC-4637-A912-725D59B8D748@gmail.com> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-Trace: ger.gmane.org 1405063761 14198 80.91.229.3 (11 Jul 2014 07:29:21 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 11 Jul 2014 07:29:21 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBC5JHI7A7ALRBR5E72OQKGQE4LO46RY@isocpp.org Fri Jul 11 09:29:14 2014 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-vc0-f198.google.com ([209.85.220.198]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1X5VGa-0007II-NE for gclcip-std-proposals@m.gmane.org; Fri, 11 Jul 2014 09:29:12 +0200 Original-Received: by mail-vc0-f198.google.com with SMTP id hy4sf300857vcb.1 for ; Fri, 11 Jul 2014 00:29:11 -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=kRqK5TvUmQlB3iMo1rswltRLOPXtWt2JFIpipLa5NA4=; b=GRLBmRJoKeGb0pBHzOCe8OQfenffqPSAqxSaZoeWqoTvga9QQsE7nBLuaOEAMi0h1C OBN9Yk32n5kx8fR1Q8PupHDVqKUBHXVkyImbxkHBJwONvCvWQvKcp4XgRQXwp23o4W99 39eJqt1zmITK9FGnENWhKFhkWdMLqMUZ2nPVCE2ctpi0CUGmXkiy7Icm7+RTdFtAWXkH HLRvWQ69tEuahpyLS4NkwgjSMMgUy1qqRylvfNmVeP+Ntp7WJuafKJZM2+T1lzQhruEk 169w/keRplqiWu3msh964+ev7GxfdA2dx99b95ulTZbqXv1ilDQ4qDlZnoWfX0FMtEK3 cOMw== X-Gm-Message-State: ALoCoQkzJVXjUGt/c0ZD6m7Qqy5Pp31RaPcBlgoQmD1+DdYPKZ0isrwfNQ1z8n/5ug+mv/fiNz5Q X-Received: by 10.236.161.8 with SMTP id v8mr1175622yhk.0.1405063751788; Fri, 11 Jul 2014 00:29:11 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.140.96.6 with SMTP id j6ls313328qge.89.gmail; Fri, 11 Jul 2014 00:29:11 -0700 (PDT) X-Received: by 10.224.13.139 with SMTP id c11mr89368870qaa.77.1405063751206; Fri, 11 Jul 2014 00:29:11 -0700 (PDT) Original-Received: from mail-qg0-x234.google.com (mail-qg0-x234.google.com [2607:f8b0:400d:c04::234]) by mx.google.com with ESMTPS id k12si2210217qav.129.2014.07.11.00.29.11 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Fri, 11 Jul 2014 00:29:11 -0700 (PDT) Received-SPF: pass (google.com: domain of ville.voutilainen@gmail.com designates 2607:f8b0:400d:c04::234 as permitted sender) client-ip=2607:f8b0:400d:c04::234; Original-Received: by mail-qg0-f52.google.com with SMTP id f51so610009qge.39 for ; Fri, 11 Jul 2014 00:29:11 -0700 (PDT) X-Received: by 10.224.57.148 with SMTP id c20mr12120309qah.31.1405063751072; Fri, 11 Jul 2014 00:29:11 -0700 (PDT) Original-Received: by 10.224.31.137 with HTTP; Fri, 11 Jul 2014 00:29:11 -0700 (PDT) In-Reply-To: <6598852E-AFEC-4637-A912-725D59B8D748@gmail.com> 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:c04::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:11828 Archived-At: On 11 July 2014 03:56, David Krauss wrote: > I notice some proposals N4115 and N3728 (formerly N3416) advocating > extensions for manipulation of parameter packs. I think they are rejecting > std::tuple unnecessarily, potentially adding legwork for users. > > From N3728: > > Compilation speed is often gating in metaprogramming. In implementating the > bases trait proposed in N3729 as a g++4.7 extension, I compared the > performance of returning a tuple type giving all the base classes of a class > with returning a simple typelist class containing no members and no > recursive expansion. The simple typelist class was 60 times faster to > compile. A built-in parameter list would presumably be even faster than > that. Given that the recursive member generation in tuple provides no > benefit for typelists, tuple-based typelists should probably be avoided for > performance reasons alone. I don't see how a 60x difference in compilation speed is "rejecting tuple unnecessarily". -- --- You received this message because you are subscribed to the Google Groups "ISO C++ Standard - Future Proposals" group. 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