220 28534 article Path: news.gmane.org!.POSTED!not-for-mail From: Ville Voutilainen Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: A plea to reconsider adding Structured Bindings to language Date: Wed, 5 Oct 2016 17:26:07 +0300 Lines: 32 Approved: news@gmane.org Message-ID: References: <201610051238.17863.marc.mutz@kdab.com> <201610051300.02280.marc.mutz@kdab.com> <201610051411.30312.marc.mutz@kdab.com> <073a7698-1388-4858-b6fa-b2b62a4fb6f1@isocpp.org> 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 1475677596 22440 195.159.176.226 (5 Oct 2016 14:26:36 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Wed, 5 Oct 2016 14:26:36 +0000 (UTC) To: "ISO C++ Standard - Future Proposals" Original-X-From: std-proposals+bncBC5JHI7A7ALRBAE32S7QKGQEWJ3KJWI@isocpp.org Wed Oct 05 16:26:29 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-vk0-f70.google.com ([209.85.213.70]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1brn95-0002YA-NC for gclcip-std-proposals@m.gmane.org; Wed, 05 Oct 2016 16:26:07 +0200 Original-Received: by mail-vk0-f70.google.com with SMTP id 83sf130036066vkd.3 for ; Wed, 05 Oct 2016 07:26:10 -0700 (PDT) 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=86NsRcswEU3NwxDsNslGzPU/9tp7SPhrt4AKt6tDBHc=; b=Pw1ilxf2Y5Hbq6AhdbRvHZTDryK/XdQnVF0w4wCmz5/uRE39upe2W6lWqbz9WZQFDN qHjaApObWEpzKAo2NpMP/Bss9rr9GUrGF8EdwdXt9CGV5qNttLtb6cQvSBH0HaNI0uUJ UkekGTFyK1A86aCVe+RLyjhKxfQFvT1er+0AjgQ4t+3dXGUiK9VlreW829NC2icNEwBK Wqi/zjE7s40hGCZ4TqEuh3dCG2fwyJxy5GCXJLNJUsXLeqODI3rD0Sy7cXKAgRLKhjKM 4O6REJUQIuu0gyDtpSiJQMspxiiVWiaQNsaAAGi+buC8UKYNLXBLg47V8uoqHex9yGQK ANnw== 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: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=86NsRcswEU3NwxDsNslGzPU/9tp7SPhrt4AKt6tDBHc=; b=Yc8Whg/6FRCPxrAEDqYTrBbNuDE05TNzQC0COOxQwCSHD1FrqU+89n0QGiMhcP6JsH cmbiWqdMKjGSF8pfqXL/41GeoJzUbzNXM7gv9QOpaPJzWKZWUQ7v+IqosohZ1JO4lzoE 6OG3fFF9y84JMDuKmFf7nK+g0aHx1O2jQux7LssunxSQbX3dvLEOemySurzXlW3Z0h4L UZNO28ePDlwvYW//bf85ZBtbtxYQWWEJvj9xAjm6ubi/gP1N5sI52jcbD7DdjKIiaU04 BYn3emDZD9PZ1Lsg0XqK99Dc4BjKj0GaDWLUuzMJmub1583k+8U9MM2Qj5AfLRZCjYRv pbsw== X-Gm-Message-State: AA6/9Rnubqw12cd4pVnRqAMieu1mhwyYsbZOoLmRnzXOhuUESRcFzwg8uECuv9ZdrtQsGA== X-Received: by 10.107.162.83 with SMTP id l80mr2567098ioe.29.1475677569375; Wed, 05 Oct 2016 07:26:09 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.157.7.18 with SMTP id 18ls770272ote.9.gmail; Wed, 05 Oct 2016 07:26:08 -0700 (PDT) X-Received: by 10.159.37.215 with SMTP id 81mr6694425uaf.134.1475677568572; Wed, 05 Oct 2016 07:26:08 -0700 (PDT) Original-Received: from mail-vk0-x22c.google.com (mail-vk0-x22c.google.com. [2607:f8b0:400c:c05::22c]) by mx.google.com with ESMTPS id e22si16542903uaa.181.2016.10.05.07.26.08 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 05 Oct 2016 07:26:08 -0700 (PDT) Received-SPF: pass (google.com: domain of ville.voutilainen@gmail.com designates 2607:f8b0:400c:c05::22c as permitted sender) client-ip=2607:f8b0:400c:c05::22c; Original-Received: by mail-vk0-x22c.google.com with SMTP id z126so222883344vkd.0 for ; Wed, 05 Oct 2016 07:26:08 -0700 (PDT) X-Received: by 10.31.193.20 with SMTP id r20mr6737315vkf.44.1475677568250; Wed, 05 Oct 2016 07:26:08 -0700 (PDT) Original-Received: by 10.103.104.69 with HTTP; Wed, 5 Oct 2016 07:26:07 -0700 (PDT) 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:c05::22c 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:28534 Archived-At: On 5 October 2016 at 17:20, Greg Marr wrote: >> > Only if you say that you want references, using "auto &" or "auto &&". >> > If >> > you use "auto", you just get copies. >> >> You get a copy of the whole struct, not copies of individual bindings. > > > That's not what's described in the paper. Has it changed since That's what the wording of the facility does, and what the clang implementation does. > https://isocpp.org/files/papers/p0217r0.html ? See http://open-std.org/JTC1/SC22/WG21/docs/papers/2016/p0217r1.html > The binding results in individual variables, and if they're copies of the > values from the struct, there is no reason to keep the original struct > around. Except that yes there is, because if the fields depend on each other, copying them individually can break invariants. -- 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/CAFk2RUb_y9r3C99s_Sqeh7dxCkqeE-j9fCP_DbH0S7%2Bip_pF5g%40mail.gmail.com. .