220 34288 article Path: news.gmane.org!.POSTED!not-for-mail From: Eyal Rozenberg Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: Idea: Extension of structured bindings to definition of structs Date: Mon, 4 Sep 2017 18:57:39 +0200 Lines: 56 Approved: news@gmane.org Message-ID: References: <59dcbbbc-c536-4b7b-9c88-0638fb0cd58a@technion.ac.il> <7b9bf263-d3ca-42bf-aed6-4c7606782a28@isocpp.org> <1762295.OciJaA9sdk@tjmaciei-mobl1> <74349bfe-bb5a-a2ce-4142-5d46103d1d9f@technion.ac.il> <2f48bdde-a6b6-473f-96ec-8836fd8de463@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"; format=flowed X-Trace: blaine.gmane.org 1504544282 15278 195.159.176.226 (4 Sep 2017 16:58:02 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Mon, 4 Sep 2017 16:58:02 +0000 (UTC) User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:56.0) Gecko/20100101 Thunderbird/56.0 Cc: std-proposals@isocpp.org To: Nicol Bolas Original-X-From: std-proposals+bncBDHKZN7LR4ARBCMMW3GQKGQEUC6TUFY@isocpp.org Mon Sep 04 18:57:47 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-lf0-f72.google.com ([209.85.215.72]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1dougu-00030w-02 for gclcip-std-proposals@m.gmane.org; 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[192.16.191.27]) by mx.google.com with ESMTPS id c9si8305355edl.502.2017.09.04.09.57.45 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 04 Sep 2017 09:57:45 -0700 (PDT) Received-SPF: pass (google.com: domain of srs0=5sp6a=af=technion.ac.il=eyalroz@cwi.nl designates 192.16.191.27 as permitted sender) client-ip=192.16.191.27; Original-Received: from fester.cwi.nl (fester.cwi.nl [192.16.191.27]) by fester.cwi.nl (8.14.4/8.12.3) with ESMTP id v84GviFg023499; Mon, 4 Sep 2017 18:57:44 +0200 Original-Received: from [192.168.2.1] (ip565d4370.direct-adsl.nl [86.93.67.112] (may be forged)) (authenticated bits=0) by fester.cwi.nl (8.14.4/8.12.3) with ESMTP id v84Gvird023497 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=NO); Mon, 4 Sep 2017 18:57:44 +0200 In-Reply-To: <2f48bdde-a6b6-473f-96ec-8836fd8de463@isocpp.org> Content-Language: en-US X-Original-Sender: eyalroz@technion.ac.il X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of srs0=5sp6a=af=technion.ac.il=eyalroz@cwi.nl designates 192.16.191.27 as permitted sender) smtp.mailfrom=SRS0=5SP6A=AF=technion.ac.il=eyalroz@cwi.nl 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:34288 Archived-At: On 8/30/17 5:02 PM, Nicol Bolas wrote: > But the reason I'm using `auto` is because I either: > > 1) Don't need to write the name of the type, since it is obvious by > inspection > 2) Do not want to write the name of the type, since it's long, complex, etc > > Why do I need to create a /type/ that contains a bunch of such > variables? And why would I need to do it /inline/ like this? > ... See my email to Nevin Liber from a couple of minutes ago. We are _already_ creating the type in this case (at least in one of the alternatives). My - I would say tiny - suggestion is to add a bit more syntactic sugar for facilitating that, in the same vein as auto declaration of multiple non-struct variables. It makes coding the thing more fluent,. Fluency, DRY. Also, apparently, replacing a Boost Spirit X3 macro which does this for us :-) http://ciere.com/cppnow15/x3_docs/spirit/tutorials/employee___parsing_into_structs.html > Why did I make a struct out of it instead of just having a number of loose variables? ... what is the point of having this unnamed struct that uses automatically-deduced values? Who am I going to pass it to? What operations am I going to perform on it? No, you aren't - and that _is_ the whole point! If you had wanted a carefully-defined type with methods and such to pass around and expose, you would have gone to the trouble of defining it properly, and with a _name_. Instead, you just fluently create the struct, with an anonymous "throw-away" POD type, without you having to mentally bother with the definition. This is actually reason (1.) you gave for using auto... You "don't need to write the name of the type, since it is obvious by inspection." and that's what I want too. Eyal -- 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/b3969fcf-964f-a8ef-622b-a9039a852367%40technion.ac.il. .