220 30101 article Path: news.gmane.org!.POSTED!not-for-mail From: Ville Voutilainen Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: decltype(return) Date: Thu, 29 Dec 2016 20:32:20 +0200 Lines: 30 Approved: news@gmane.org Message-ID: References: <658f00ff-7a02-7c04-3fcb-6ac7f45b777b@scylladb.com> <425f6577-b92d-40f3-8d0d-64668351edf5@isocpp.org> <5863DB05.3030805@gmail.com> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-Trace: blaine.gmane.org 1483036345 2407 195.159.176.226 (29 Dec 2016 18:32:25 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Thu, 29 Dec 2016 18:32:25 +0000 (UTC) To: "ISO C++ Standard - Future Proposals" Original-X-From: std-proposals+bncBC5JHI7A7ALRBNNNSXBQKGQE7YEHG5Y@isocpp.org Thu Dec 29 19:32:21 2016 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 1cMfUv-0007te-Ij for gclcip-std-proposals@m.gmane.org; Thu, 29 Dec 2016 19:32:17 +0100 Original-Received: by mail-yw0-f198.google.com with SMTP id s68sf422790569ywg.7 for ; Thu, 29 Dec 2016 10:32:22 -0800 (PST) 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=+mVhcAiKhhMDCYcweAIPYvVHoS3OGDlKw7rdOvOKGWg=; b=j8vFQXmcylKuGIUcq9vQG6kyXEYQk6P5nF7tWnDZO0paFQyzWAqZSFDNgZnOb8OcjA WG/POc6RcqW+WKvUkxoC5DQsdW0Qz+5NxgyeZ7f3LJ9JVT2/KR65Con/4FGN98M01HrC n3eqEy4CnvI7VwW11Ftg7Qp4BjMZz/EWmPH/7r9Y4Q5D7Hmbt9RjTH7FfZqnQyyE08JT I7/ey6r43HGIi1Tcdq2yksdUVB+Rp7c/tjvUaFtEZvAGX+DD6d2wy9eA8Z8OmnViVnN2 MasNVd7wy40yA/1yvqKKpzdsmH66i0o98djmuMJYNzGNMWa9rKkRjjUiicNfs/OBfMX1 cjMg== 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=+mVhcAiKhhMDCYcweAIPYvVHoS3OGDlKw7rdOvOKGWg=; b=XZic/dEKK3PlgNq3P+53vtJ8PYLUKDGvGdiPuM6kA5FH0G5yLjAhnxLEEUwzgSHL5p df3yxa+Xj2yAbsz+t16bnUE4gF8/vv2BQ5NIsy71xrNdOgb3Fguvepai87T0CvnqtZ93 M5M5T8sBje8PmqoOl2gWsOJ7wpJlIfoaHLCMegD8YC3mY33yTot5W1Z/S8JS3G2PBIbs FlBey3pSwitmEhWX5f/EwPzMQUmehpfWdDXcHCO1Ni6RtgYyx8Z0jpBJPhpXO2xJQNjV RPYTJM9Sfoa/bz++uCO0jdUZDnzD02FsQ1gHYjxsF+fh2Q0lL1Ffun+zS2UPvOi6LcRd cN3w== X-Gm-Message-State: AIkVDXJX2smjEIalLoLGrwSg2Ma5Z7kTeHX4FDX5mbS4INqqtE2VS4yYu6D4gXHF7OJNhg== X-Received: by 10.129.102.5 with SMTP id a5mr12312721ywc.141.1483036342349; Thu, 29 Dec 2016 10:32:22 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.157.54.168 with SMTP id h37ls10171111otc.45.gmail; Thu, 29 Dec 2016 10:32:21 -0800 (PST) X-Received: by 10.176.71.86 with SMTP id i22mr19620243uac.31.1483036341436; Thu, 29 Dec 2016 10:32:21 -0800 (PST) Original-Received: from mail-ua0-x233.google.com (mail-ua0-x233.google.com. [2607:f8b0:400c:c08::233]) by mx.google.com with ESMTPS id a67si13384477vkc.249.2016.12.29.10.32.21 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 29 Dec 2016 10:32:21 -0800 (PST) Received-SPF: pass (google.com: domain of ville.voutilainen@gmail.com designates 2607:f8b0:400c:c08::233 as permitted sender) client-ip=2607:f8b0:400c:c08::233; Original-Received: by mail-ua0-x233.google.com with SMTP id 88so231564723uaq.3 for ; Thu, 29 Dec 2016 10:32:21 -0800 (PST) X-Received: by 10.176.85.24 with SMTP id t24mr34594912uaa.21.1483036341082; Thu, 29 Dec 2016 10:32:21 -0800 (PST) Original-Received: by 10.103.50.74 with HTTP; Thu, 29 Dec 2016 10:32:20 -0800 (PST) In-Reply-To: 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:f8b0:400c:c08::233 as permitted sender) smtp.mailfrom=ville.voutilainen@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:30101 Archived-At: On 29 December 2016 at 20:10, Marc wrote: > On Wednesday, December 28, 2016 at 4:42:42 PM UTC+1, Ville Voutilainen > wrote: >> >> On 28 December 2016 at 17:32, Matthew Woehlke >> wrote: >> > template >> > auto foo(A a, B b, ...) -> decltype(a * b) >> > { ... } >> > >> > How would you write a typedef of that? Assume that `A` and/or `B` >> > *cannot be default constructed*. >> >> template using ab_prod = decltype(declval() * >> declval()); > > > This does not look equivalent to me, declval would be closer. Probably. The point being that whether a type is or is not default-constructible doesn't hurt the ability to write such a typedef. -- 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/CAFk2RUbmHo7zVd1AgpNHMgncJkfFq4EB_JVX10LOK3E1BTSP8A%40mail.gmail.com. .