220 34220 <74349bfe-bb5a-a2ce-4142-5d46103d1d9f@technion.ac.il> 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: Wed, 30 Aug 2017 09:59:25 +0200 Lines: 80 Approved: news@gmane.org Message-ID: <74349bfe-bb5a-a2ce-4142-5d46103d1d9f@technion.ac.il> References: <59dcbbbc-c536-4b7b-9c88-0638fb0cd58a@technion.ac.il> <7b9bf263-d3ca-42bf-aed6-4c7606782a28@isocpp.org> <1762295.OciJaA9sdk@tjmaciei-mobl1> 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 1504079995 5954 195.159.176.226 (30 Aug 2017 07:59:55 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Wed, 30 Aug 2017 07:59:55 +0000 (UTC) User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDHKZN7LR4ARB3XATHGQKGQEKAGOYDI@isocpp.org Wed Aug 30 09:59:49 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-wm0-f71.google.com ([74.125.82.71]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1dmxuS-0000eE-EH for gclcip-std-proposals@m.gmane.org; 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[192.16.191.27]) by mx.google.com with ESMTPS id j4si4160131edk.222.2017.08.30.00.59.41 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 30 Aug 2017 00:59:41 -0700 (PDT) Received-SPF: pass (google.com: domain of srs0=r1jhs=aa=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 v7U7xfiq007276; Wed, 30 Aug 2017 09:59:41 +0200 Original-Received: from [10.180.31.178] (host191-2.natpool.mwn.de [138.246.2.191]) (authenticated bits=0) by fester.cwi.nl (8.14.4/8.12.3) with ESMTP id v7U7xVfh007269 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES128-SHA bits=128 verify=NO); Wed, 30 Aug 2017 09:59:39 +0200 In-Reply-To: Content-Language: en-GB X-Original-Sender: eyalroz@technion.ac.il X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of srs0=r1jhs=aa=technion.ac.il=eyalroz@cwi.nl designates 192.16.191.27 as permitted sender) smtp.mailfrom=SRS0=r1jhs=AA=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:34220 Archived-At: You would be using an unnamed struct for the same reason you use an "unnamed type" for non-struct variables with auto. We write: auto x = expr; although we could write using whatever_t = decltype(expr); // ... whatever_t x = expr; except we do it for several values which are grouped together in a struct. The second option does the exact same thing, but it's annoying and verbose. On 27/08/17 16:11, Nicol Bolas wrote: > difficult to understand the code when actually using a tuple, why would > I be using an /unnamed/ struct to solve this? Would it not make more > sense to do this: > > | > structRealName > { > RealName(conststd::tuple&); > > inta_member; > doubleother_member; > }; > | > > And then in the actual function: > > | > RealNames =std::make_tuple(1,2.3); > | > > This improves code reuse, since `RealName` can be used in multiple > places. It improves readability, since `RealName` would convey semantic > information about the collection of values that `decltype(s)` cannot. > And so forth. The trivial repetition of typing the type names in two (or > even three) places in `RealName` will be meaningless next to how often > `RealName` is used. > > Presumably, the reason I'm /not/ using structured binding is because I > want to pass the collection `s` around to other people, yes? Otherwise, > you would just use structured binding to provide the semantic info. > Given that this is the case, we need a proper name so that we understand > what this aggregate actually means. > > If this is a one-off case, where you're only calling one function that > has a `tuple` API in one place... why are you creating an object for the > values at all? If it's a one-off, use structured binding, or just > tough-through the `get<>` interface for that one function. > > What circumstances would I be in where I would be writing an /inline > struct/ to convert this object? If it happens frequently enough to > obfuscate my code, the best solution is a named struct. If it's not that > frequent, just use structured binding or the actual return value. > > -- > 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/ff2ceb41-caca-4659-9a7d-4da9c2046810%40isocpp.org > . -- 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. 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