220 28732 article Path: news.gmane.org!.POSTED!not-for-mail From: Matthew Woehlke Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: A plea to reconsider adding Structured Bindings to language Date: Wed, 12 Oct 2016 10:19:50 -0400 Lines: 46 Approved: news@gmane.org Message-ID: 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 X-Trace: blaine.gmane.org 1476283257 19666 195.159.176.226 (12 Oct 2016 14:40:57 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Wed, 12 Oct 2016 14:40:57 +0000 (UTC) User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBC37LBFWUIFBBYUW7G7QKGQEFCWAJMA@isocpp.org Wed Oct 12 16:40:53 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-lf0-f70.google.com ([209.85.215.70]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1buKhs-00028Z-W3 for gclcip-std-proposals@m.gmane.org; Wed, 12 Oct 2016 16:40:33 +0200 Original-Received: by mail-lf0-f70.google.com with SMTP id b81sf28763600lfe.1 for ; Wed, 12 Oct 2016 07:40:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=to:from:subject:date:lines:message-id:references:mime-version :user-agent:in-reply-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=xbPW8G6w+J/9JQyHwCNSmHEoM6U2wVyjz0vN5K7dOBo=; b=JWeZbo2AedoRmunjS2vFZpMn414FwyQYv60+in2eZvH0AUDoLmbMiGuMJ4TjNaQpWM 5v5PT93wRV5a1jjX7RNqP1eAAlUuOqXD1SfHCNOciWaA0tlIjaAkxXNQsTjhQ93xEIk2 9vVZYjkr/7D5Mj1O8gpwGzlGmDQdHuobfQpsdiIcm+qGNKn52BA2AujNnuSF9Li7VoVw zXLKPIqPCdZPmZhgZXQ4ynxjT+zyJ7tQGJqGzfkpblq5j/eX5Kk3duRuL//NNFO1/80z h3qvLsJYkK0vYNwvLZYtU2fe9oTVzB4CNRQwjp1QXkq2iIX03GogfvWnO5Cknd0V2YKq 4IvQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:to:from:subject:date:lines:message-id:references :mime-version:user-agent:in-reply-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=xbPW8G6w+J/9JQyHwCNSmHEoM6U2wVyjz0vN5K7dOBo=; b=GGQ91wt2ao7k63GPR0mgz8yQQFoFZ9uFYVReejOzpYymDP0XTmJ1I6EXafH+vhbSwk WnNRhRN8pyklxFD8v0Ja4M/VdtmZHFQFiJebnUzNoYJ8T9IFy3NVde1Uy1r6JH6HdvMp XFmbdrmCufAGbFYeML2zL1g00gLCUDqZ771chRsWST87/bt2dDPwyoBuoVozlJqioi4g dChIaLqbqK/IrG8ZmpF/8XCqZci8dFGDmJrDY5RBg3kVbPU8Na33qLMXsnjegoXjAYNN XWnLKh4U2xCPLC0XhytwSdcUuJJzKUjvTgqpBbLJf3LCNJpm7LpZ5ri+O9xGm9g1YhLh zUgg== X-Gm-Message-State: AA6/9RkZiWHyMPiBExzeSuh4irzDbqI8+Y6Ugk7KKOYlgfhxTr5BGGeDzwxOinK6GuhXuA== X-Received: by 10.194.6.227 with SMTP id e3mr176463wja.11.1476283235203; Wed, 12 Oct 2016 07:40:35 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.25.205.140 with SMTP id d134ls429645lfg.33.gmail; Wed, 12 Oct 2016 07:40:34 -0700 (PDT) X-Received: by 10.25.165.71 with SMTP id o68mr1582898lfe.99.1476283234208; Wed, 12 Oct 2016 07:40:34 -0700 (PDT) Original-Received: from blaine.gmane.org ([195.159.176.226]) by mx.google.com with ESMTPS id o137si4976820lfo.33.2016.10.12.07.40.34 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 12 Oct 2016 07:40:34 -0700 (PDT) Received-SPF: neutral (google.com: 195.159.176.226 is neither permitted nor denied by best guess record for domain of gclcip-std-proposals@m.gmane.org) client-ip=195.159.176.226; Original-Received: from list by blaine.gmane.org with local (Exim 4.84_2) (envelope-from ) id 1buKhS-0007FL-Ee for std-proposals@isocpp.org; Wed, 12 Oct 2016 16:40:06 +0200 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 39 Original-X-Complaints-To: usenet@blaine.gmane.org In-Reply-To: <201610051238.17863.marc.mutz@kdab.com> X-Original-Sender: mwoehlke.floss@gmail.com X-Original-Authentication-Results: mx.google.com; spf=neutral (google.com: 195.159.176.226 is neither permitted nor denied by best guess record for domain of gclcip-std-proposals@m.gmane.org) smtp.mailfrom=gclcip-std-proposals@m.gmane.org; dmarc=fail (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:28732 Archived-At: (Apologies if this posts twice; the original appears to have gotten lost.) On 2016-10-05 06:38, Marc Mutz wrote: > I heard about Structured Bindings for the first time at CppCon this year, and > I'd like to raise my concerns, esp. since half of the panel was crazy about > them. > > The reaons it's horrible, is because it reverses the C++ principle that the > implementor of a library should have to do the work, not the user. > > It reverses the principle by requiring the *caller* to choose the names of the > values returned, when it should be the implementor of the function who chooses > the names. > > 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. > > IMHO, the correct solution to the multiple return value problem is to return a > struct with properly named fields, not a pair and not a tuple. > > I believe there's a proposal for allowing to define structs in function > declarations already, but I failed to find it. You are likely thinking of http://wg21.link/p0222 and http://wg21.link/p0224. (I still need to merge and dust those off one of these days...) I agree that P0222 would be *much* better than returning pair/tuple, but I also don't have a problem with assignment unpacking. I'm not convinced that return values are so much more brittle than parameters that they will make API stability much worse. (That said, I wouldn't be overly heartbroken if S.B. was held back for a revision. I'm not convinced that we've solved bitfields adequately.) -- Matthew -- 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/ntlgq3%243tk%242%40blaine.gmane.org. .