220 40089 <7da3d89d-febe-9b88-0774-9772611d8475@gmail.com> article Path: news.gmane.org!.POSTED!not-for-mail From: Matthew Woehlke Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Named Parameters for C++ Date: Wed, 29 Aug 2018 11:00:09 -0400 Lines: 44 Approved: news@gmane.org Message-ID: <7da3d89d-febe-9b88-0774-9772611d8475@gmail.com> References: <0341abf7-070d-4dd6-88d3-b7072b991cd4@isocpp.org> <0fe2a8da-3442-edbe-7bdf-40d6b1c90d1b@gmail.com> <28f2a655-1a1b-4386-9f76-c16ddb1647e6@isocpp.org> <4f02dc49-5945-f245-c7ca-76d2d9ab83be@gmail.com> <8693c5c4-d544-1ee0-ae12-b3c2f5c1537f@gmail.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 1535554688 32167 195.159.176.226 (29 Aug 2018 14:58:08 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Wed, 29 Aug 2018 14:58:08 +0000 (UTC) User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBC37LBFWUIFBB7HJTLOAKGQE3MBKE5I@isocpp.org Wed Aug 29 16:58:04 2018 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-qk0-f197.google.com ([209.85.220.197]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1fv1v0-0008Cn-RS for gclcip-std-proposals@m.gmane.org; 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[66.194.253.20]) by smtp.googlemail.com with ESMTPSA id p19-v6sm2531541qtc.56.2018.08.29.08.00.09 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 29 Aug 2018 08:00:10 -0700 (PDT) Openpgp: preference=signencrypt In-Reply-To: Content-Language: en-US X-Original-Sender: mwoehlke.floss@gmail.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b="Jgi/2J9S"; spf=pass (google.com: domain of mwoehlke.floss@gmail.com designates 209.85.220.41 as permitted sender) smtp.mailfrom=mwoehlke.floss@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Spam-Checked-In-Group: std-proposals@isocpp.org 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:40089 Archived-At: On 2018-08-29 10:32, Jake Arkinstall wrote: > Though we still have to force them to work in a certain way because > instruction ordering needs to be consistent. > > void f(int a, int b); > > int x = 0; > f(.b = ++x, .a = ++x); > > Does 'a' get given the value 1 or 2? AFAIUI, this is unspecified. Let me clarify: void f(int a, int b); int x = 0; f(++x, ++x); *This is (still) unspecified* (again, AIUI). We guarantee that the arguments to `f` will be 1 and 2 (not 1 and 1, or 2 and 2, which was *not* true before C++17), but not whether you will get a=1, b=2 or a=2, b=1. Reordering won't make this any worse. > f(.a=some_expensive_function(), .b=.a); > > Might be useful to someone out there. Right now, even with any of the named arguments ideas, that's a syntax error. It *might* be useful, but I think it needs its own, separate proposal, if we ever get to the point where it would be feasible to consider it. -- 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. 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