220 36331 <4a8c1326-d560-4d57-b8ab-afc85d627166@isocpp.org> article Path: news.gmane.org!.POSTED!not-for-mail From: bastienpenava@gmail.com Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Now that the std::forward alternative has been rejected Date: Sun, 24 Dec 2017 22:17:11 -0800 (PST) Lines: 247 Approved: news@gmane.org Message-ID: <4a8c1326-d560-4d57-b8ab-afc85d627166@isocpp.org> References: <1a84e87b-c045-408c-9828-b1aba2185a0a@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_14791_1304117373.1514182631317" X-Trace: blaine.gmane.org 1514182519 17948 195.159.176.226 (25 Dec 2017 06:15:19 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Mon, 25 Dec 2017 06:15:19 +0000 (UTC) Cc: mihailnajdenov@gmail.com To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBCG3XHNI6IDRB2FPQLJAKGQEHPCAQEA@isocpp.org Mon Dec 25 07:15:14 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ua0-f198.google.com ([209.85.217.198]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1eTM2Z-0003za-93 for gclcip-std-proposals@m.gmane.org; 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Sun, 24 Dec 2017 22:17:13 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.31.150.196 with SMTP id y187ls2574787vkd.10.gmail; Sun, 24 Dec 2017 22:17:12 -0800 (PST) X-Received: by 10.31.171.73 with SMTP id u70mr1988682vke.10.1514182631940; Sun, 24 Dec 2017 22:17:11 -0800 (PST) In-Reply-To: <1a84e87b-c045-408c-9828-b1aba2185a0a@isocpp.org> X-Original-Sender: BastienPenava@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:36331 Archived-At: ------=_Part_14791_1304117373.1514182631317 Content-Type: multipart/alternative; boundary="----=_Part_14792_2065278301.1514182631318" ------=_Part_14792_2065278301.1514182631318 Content-Type: text/plain; charset="UTF-8" On Monday, December 25, 2017 at 5:28:05 AM UTC+1, Nicol Bolas wrote: > > On Sunday, December 24, 2017 at 8:17:30 PM UTC-5, bastie...@gmail.com > wrote: >> >> On Sunday, December 24, 2017 at 9:47:30 AM UTC+1, mihailn...@gmail.com >> wrote: >>> >>> Hello, I read >>> >>> the proposal "Forward without forward" has been rejected. >>> >>> Now, can we please reconsider fixing forward "the right way" even if it >>> involves hacks? >>> >>> And by "the right way" a mean, of course, let the template param be >>> omitted. >>> >>> Why is the right way? Multiple reasons: >>> >>> >>> 1. Preserve the API taught for close to 10 years now. >>> >>> actually this is false.std::forward without template param is valid and >> your change would change its meaning. >> >>> >>> 1. Remove confusion for EVERYONE learning C++11+, be at a beginner >>> or advanced user. >>> 2. The param is confusing on its own (to a beginner) - should I pass >>> T or T&&, what happens if I pass const T, const T&&, T*? Do I really have >>> options here?!? Or Just One Right Param?!?! >>> >>> std::forward is fairly easy to explain to a beginner. >> > > No, it's not. It's easy to tell a beginner what they have to do and when > they have to do it. But explaining what it actually is doing (beyond > simplistic "it's forwarding the parameters") is not easy. > > > But even if it wasn't the case, cases where std::forward is required are >> not for beginners (library writing, etc...). >> > > Nonsense. Writing passthrough functions should be in* everyone's* > toolkit, not just "library writers". Thinking like that is what makes > people think that template metaprogramming is OK, because regular C++ > programmers shouldn't want to do things like iterate over things at compile > time or somesuch. > good passthrough functions will never be easy to write in C++. The committee is not interested. The lambda abbreviated proposal by the same person (which also applied to functions) aimed to make it easier and got shutdown hard. > > Making the powers of the language more accessible is not a bad thing. > What makes you think I disagree with that ? If anything I am an advocate of the original proposal of Barry Revzin. I disagree though that It should be fixed by creating an implementation defined library solution that violates the behaviour of a function and its arguments. We don't need more weird exceptions. > > >>> 1. The param is an ugly nightmare to pass in [](auto) {} scenario >>> >>> C++20 has template parameter for lambda so this is no longer a valid >> issue. >> > > Which only trades one verbosity for another. > Being ugly and being verbose are two different things. > > [](auto&&... args) {return some_func(std::forward(args > )...);} > > vs. > > []