220 34158 article Path: news.gmane.org!.POSTED!not-for-mail From: Zhihao Yuan Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: Structured bindings with polymorphic lambdas Date: Sat, 26 Aug 2017 16:07:27 -0500 Lines: 42 Approved: news@gmane.org Message-ID: References: <8497b31b-7c9d-4334-ac22-0809c958cb93@isocpp.org> <15a70d94-e039-4f82-ba01-bde9d3fbacbd@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 1503781659 28463 195.159.176.226 (26 Aug 2017 21:07:39 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sat, 26 Aug 2017 21:07:39 +0000 (UTC) Cc: rmn100@gmail.com To: "std-proposals@isocpp.org" Original-X-From: std-proposals+bncBCSKRWMD4EHBBEOGQ7GQKGQEFESHC5Q@isocpp.org Sat Aug 26 23:07:34 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-yw0-f199.google.com ([209.85.161.199]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1dliIe-0006fY-Db for gclcip-std-proposals@m.gmane.org; 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[184.173.153.196]) by mx.google.com with UTF8SMTPS id 32si8773302qth.25.2017.08.26.14.07.29 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 26 Aug 2017 14:07:29 -0700 (PDT) Received-SPF: pass (google.com: domain of bounce+3f9131.69110-std-proposals=isocpp.org@miator.net designates 184.173.153.196 as permitted sender) client-ip=184.173.153.196; Original-Sender: zy@miator.net X-Mailgun-Sending-Ip: 184.173.153.196 X-Mailgun-Sid: WyI3MTBkYiIsICJzdGQtcHJvcG9zYWxzQGlzb2NwcC5vcmciLCAiNjkxMTAiXQ== Original-Received: from mail-qk0-f169.google.com (mail-qk0-f169.google.com [209.85.220.169]) by mxa.mailgun.org with ESMTP id 59a1e310.7fe2e8058670-smtp-out-n01; Sat, 26 Aug 2017 21:07:28 -0000 (UTC) Original-Received: by mail-qk0-f169.google.com with SMTP id p67so12393936qkd.2 for ; Sat, 26 Aug 2017 14:07:28 -0700 (PDT) X-Received: by 10.55.9.20 with SMTP id 20mr3340855qkj.355.1503781647839; Sat, 26 Aug 2017 14:07:27 -0700 (PDT) Original-Received: by 10.237.41.1 with HTTP; Sat, 26 Aug 2017 14:07:27 -0700 (PDT) In-Reply-To: <15a70d94-e039-4f82-ba01-bde9d3fbacbd@isocpp.org> X-Gmail-Original-Message-ID: X-Original-Sender: zy@miator.net X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@miator.net header.s=krs header.b=gOFKDZiZ; spf=pass (google.com: domain of bounce+3f9131.69110-std-proposals=isocpp.org@miator.net designates 184.173.153.196 as permitted sender) smtp.mailfrom=bounce+3f9131.69110-std-proposals=isocpp.org@miator.net 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:34158 Archived-At: On Fri, Aug 25, 2017 at 2:19 PM, Curious wrote: > >> Also, now you need to explicitly specify the order in which these >> decompositions happen. That is, if you have two structured binding >> parameters, which one gets decomposed first? At the very least, you should >> explicitly state that there is no order. > > In my mind they should follow the same order as for a regular function, > with the decompositions happening in the same order as constructions of the > parameters. > In your latest draft, you choose to decompose inside function body, so I have a further suggestion: entirely split the decomposition step from the parameter copy-init step and define the decomposition order to be left-to-right. [] (auto [a, b] /* underlying object x */, auto [c, d] /* underlying object y */) {...} When invoking this function, copy-init x and y in unspecific order, then decompose x into a and b, then decompose y into c and d. This can further simplify the model, because that will be no difference from [] (auto x, auto y) {...} from the caller's point of view. -- Zhihao Yuan, ID lichray The best way to predict the future is to invent it. _______________________________________________ -- 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/CAGsORuDZ%3DTVXNXr5NfZv-fry_kCRkmp_0%2BkNy59EqoRgr_BzPg%40mail.gmail.com. .