220 28522 <201610051300.02280.marc.mutz@kdab.com> article Path: news.gmane.org!.POSTED!not-for-mail From: Marc Mutz Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: A plea to reconsider adding Structured Bindings to language Date: Wed, 5 Oct 2016 13:00:02 +0200 Organization: KDAB Lines: 44 Approved: news@gmane.org Message-ID: <201610051300.02280.marc.mutz@kdab.com> References: <201610051238.17863.marc.mutz@kdab.com> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Trace: blaine.gmane.org 1475665106 7561 195.159.176.226 (5 Oct 2016 10:58:26 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Wed, 5 Oct 2016 10:58:26 +0000 (UTC) Cc: Ville Voutilainen , Herb Sutter , Bjarne Stroustrup , Gabriel Dos Reis To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCRPXDOU7ECRBQ5Z2O7QKGQESKX2U7A@isocpp.org Wed Oct 05 12:58:22 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-pa0-f72.google.com ([209.85.220.72]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1brjtq-0008N1-0V for gclcip-std-proposals@m.gmane.org; Wed, 05 Oct 2016 12:58:10 +0200 Original-Received: by mail-pa0-f72.google.com with SMTP id bv10sf441805013pad.2 for ; Wed, 05 Oct 2016 03:58:12 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:sender:from:organization:to:subject:date:cc :references:in-reply-to:mime-version:content-transfer-encoding :message-id: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=SmDiSSjbFO3/JoHJ0NISag45To9vpSJNL1oWDhh2ecU=; b=mzV6x1VF8cGbNOh0RrwK9mUizHKL8M90JBxteheEL5h6R2TobpwvIj4zNh6QSDgmLU aaDhxr6k859czjK2ZNv4PG6Gqw5u5jppXKRMKZAS9ovir9KeEKNBipyjnk+8sV26IfQf yNZeIgIYrZ8JEr98H5fQgVu4tKlWqn9BXskUe8QJI8LVJkqgmLEdVT9ax9oCV/y8fpNE FO1E86fdyPbBapnmGRBw1/6DpVx0+b0nC4+AWGmyYxaJJpvhFTA25jBOKae4zmbaarcy 7o2qzHal2xXIX/gTK+LRLgPIuM+N63Cr84lzp/dtGRUonym/eKGkhnA3CD X-Gm-Message-State: AA6/9RnYX9Kg35qFVdjih6DvJTibUfygn0yR8wgCqFs/ErByueJF59QlLziqI/DUKWwaXg== X-Received: by 10.98.23.147 with SMTP id 141mr816562pfx.41.1475665091745; Wed, 05 Oct 2016 03:58:11 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.157.15.105 with SMTP id 96ls373141ott.41.gmail; Wed, 05 Oct 2016 03:58:11 -0700 (PDT) X-Received: by 10.37.17.6 with SMTP id 6mr6385799ybr.148.1475665091016; Wed, 05 Oct 2016 03:58:11 -0700 (PDT) Original-Received: from mail.kdab.com (mail.kdab.com. [176.9.126.58]) by mx.google.com with ESMTPS id e142si5411284ywa.11.2016.10.05.03.58.10 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 05 Oct 2016 03:58:10 -0700 (PDT) Received-SPF: pass (google.com: domain of marc.mutz@kdab.com designates 176.9.126.58 as permitted sender) client-ip=176.9.126.58; X-Virus-Scanned: amavisd-new at kdab.com Original-Sender: marc@kdab.com In-Reply-To: X-Original-Sender: marc.mutz@kdab.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of marc.mutz@kdab.com designates 176.9.126.58 as permitted sender) smtp.mailfrom=marc.mutz@kdab.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:28522 Archived-At: On Wednesday 05 October 2016 12:40:38 Ville Voutilainen wrote: > On 5 October 2016 at 13:38, Marc Mutz wrote: > > In conjunction with auto deduction, the caller choosing the names means > > that the code becomes brittle in the face of changes to the return type, > > e.g. when reordering fields to fill padding holes. > > There have been discussions about that, especially about fields change > their types. And? What was the outcome? > > Structured Bindings would be acceptable if, like scripting languages, we > > didn't have anything else to work with. > > > > But we do: We can return a struct. > > Structured bindings work with structs as well. If you think structured > bindings mean > you must return a tuple, you're mistaken. Yes, I know that. But if I return a struct with proper names, I don't need SB to handle it. Indeed, it would be counter-productive to have to find names for SB if can access the names the implementor chose with C-space in my IDE from the auto variable that stores the return type. > > I fear Structured Bindings will lead to an explosion of *really* bad API > > that returns std::pair or std::tuple when it should return a small > > struct with > > C++ programmers are not idiots. C++ programmers are humans, though. We all make mistakes. Even Alex Stepanov did. The art is to not repeat them. Thanks, Marc -- Marc Mutz | Senior Software Engineer KDAB (Deutschland) GmbH & Co.KG, a KDAB Group Company Tel: +49-30-521325470 KDAB - Qt, C++ and OpenGL Experts .