220 19238 article Path: news.gmane.org!not-for-mail From: Sasha Unknown Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: Overloading std::begin and std::end for std::pair Date: Fri, 24 Jul 2015 15:50:54 +0300 Lines: 115 Approved: news@gmane.org Message-ID: References: <012fd35d-96fd-4775-835e-2105176c4f97@isocpp.org> <792fab39-5af7-4d95-b9ba-a5cc4aed8544@isocpp.org> <8100167.A1Y3soRlXn@tjmaciei-mobl4> <15e678b3-9b6b-4966-a7a5-1d37495fda5e@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-Trace: ger.gmane.org 1437742269 2064 80.91.229.3 (24 Jul 2015 12:51:09 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 24 Jul 2015 12:51:09 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCVLT44I5IDBBL7JZCWQKGQE7D2662A@isocpp.org Fri Jul 24 14:51:01 2015 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-qg0-f70.google.com ([209.85.192.70]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1ZIcRI-0006VX-Ka for gclcip-std-proposals@m.gmane.org; Fri, 24 Jul 2015 14:51:00 +0200 Original-Received: by qged69 with SMTP id d69sf25445481qge.2 for ; Fri, 24 Jul 2015 05:50:58 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:date :message-id:subject:from:to:content-type:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=o15w77BECLMS+oE/TYUN+XtEm84Myv26U/YllKyHztE=; b=jQ4zVbYKOatATkHUq6bLhe/nLsYIPNBU1KnNdyoTlpN9sTh9HgU2ovm6jlErUR4+ii /uheHraBBa1emB0DEhqYHvIFXDJnMdm/2M831LnFePH4nuslpH8Oe+7y0CkXL7cj+DNH AiF6HrLHYc2xAzdmDJBy3KdOecze8/uz7+9Mgtw/6rLr912oZGEWSCWlII+s/zgzXFME UZRxi8ghyT7uyyAguOXHK+d8Cy0iKatr/ywLHosgR2696hEsxeUaZz4dAvE1AewpVwBs m+7m/OzS98VnKhQUBqdrsv3AG5+iSR/wzCz7PR0EHQRFPYOje1s9uVNoL/wNBT776EIy lVow== X-Gm-Message-State: ALoCoQnKxOYNPB46dKCI9mn6m3sXnZdyYAY1ozETGOEfAaVpg1gb5P2+z3KwaVFatU1Qn+IoAa0X X-Received: by 10.129.85.86 with SMTP id j83mr14873487ywb.9.1437742258047; Fri, 24 Jul 2015 05:50:58 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.140.43.8 with SMTP id d8ls1545830qga.15.gmail; Fri, 24 Jul 2015 05:50:55 -0700 (PDT) X-Received: by 10.170.99.196 with SMTP id q187mr14626400yka.123.1437742255442; Fri, 24 Jul 2015 05:50:55 -0700 (PDT) Original-Received: from mail-yk0-x231.google.com (mail-yk0-x231.google.com. [2607:f8b0:4002:c07::231]) by mx.google.com with ESMTPS id w5si5947689ywf.213.2015.07.24.05.50.55 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 24 Jul 2015 05:50:55 -0700 (PDT) Received-SPF: pass (google.com: domain of sasha2048@gmail.com designates 2607:f8b0:4002:c07::231 as permitted sender) client-ip=2607:f8b0:4002:c07::231; Original-Received: by ykfw194 with SMTP id w194so18657304ykf.0 for ; Fri, 24 Jul 2015 05:50:55 -0700 (PDT) X-Received: by 10.129.57.193 with SMTP id g184mr14085136ywa.45.1437742255144; Fri, 24 Jul 2015 05:50:55 -0700 (PDT) Original-Received: by 10.37.81.3 with HTTP; Fri, 24 Jul 2015 05:50:54 -0700 (PDT) In-Reply-To: <15e678b3-9b6b-4966-a7a5-1d37495fda5e@isocpp.org> X-Original-Sender: sasha2048@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of sasha2048@gmail.com designates 2607:f8b0:4002:c07::231 as permitted sender) smtp.mail=sasha2048@gmail.com; dkim=pass header.i=@gmail.com; dmarc=pass (p=NONE 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:19238 Archived-At: To T. C. and Sean Middleditch: Thank you for you patience. While I don't like the this proposal of Vlad from Moscow for many reasons, I appreciate patience and level of detail in your responses. At some point in future these patience and detail-level may save some good but ugly-looking proposal. To Vlad from Moscow: 1. Just to satisfy my interest: Aren't you coming to C++ from some dynamically-typed language? 2. If n2995 and/or D4128 would be accepted, they will satisfy all your requests: for ( auto x : std::make_range( a + 3, a + 7 ) ) ...; for ( auto p : m.equal_range( 'A' ) ) ...; On Fri, Jul 24, 2015 at 10:36 AM, Vlad from Moscow wrote: > > > On Friday, July 24, 2015 at 1:58:22 AM UTC+3, Thiago Macieira wrote: >> >> On Thursday 23 July 2015 12:31:59 Vlad from Moscow wrote: >> > Could you explain why do I need some ranges when this program looks >> > clear >> > and nice without any ranges? >> >> Because you made it so that std::pair is always a range, but that >> isn't >> the case. In fact, I'd argue that most people who think of "iterating" >> over a >> pair expect it to behave as an array of two elements: the first and the >> second. >> > > There is a serious logical mistake. If for example two pointers can make up > a range this does not mean that any two pointers is a range or that any > range is two pointers. Even two iterators of the same container or two > pointers of the same array might not make a range. > > std::pair is simply a media that can store iterators. It is used in > algorithm std::mismatch where iterators does not make up a range or in the > algorithm or class methods equal_range where pointers make up a range. > > It is a responsibility of the programmer to use appropriate iterators that > are stored in the media. > > So you and Sean Middleditch attempts to substitute the meaning of std::pair > for the role like just ranges are false and confuse programmers. > It is responsibility of the programmer to correctly use std::pair in > different situations. > > With the same success you can use any valid C++ construction incorrectly. > For example you can return a reference to a local variable of a function. > Does it mean that something wrong with references and the programmers shall > not declare function return types as references? > > According to your false logic it follows that the programmers indeed shall > not declare function return types as references > > The ptoblem is why should the programmer pay for the means that he totally > need not? > > I showed already an example with std::multimap where the code looks clear > and nice. But you are saying: "Stop! Programs must not be so clear and nice. > You have to declare a class hierarchy and use these additional classes to do > a simple and entirely correct thing." > > Why do the programmer have to use a suoerstructure when he already has a > range that he stored on such a media like std::pair? > > And moreover now Sean Middleditch is even going to deform standard > algorithms with the only purpose that all programmers used his useless > superstructures where all can be done simply and clear without them. > > >> I'd expect: >> >> template const T* begin(const pair &p) >> { return &p.first; } >> >> template const T *end(const pair &p) >> { return &p.second + 1; } >> >> Which allows me to run: >> >> int main() >> { >> for (auto i : std::make_pair(1, 2)) >> cout << i << ' '; >> cout << endl; >> } >> >> output: 1 2 >> -- >> Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org >> Software Architect - Intel Open Source Technology Center >> PGP/GPG: 0x6EF45358; fingerprint: >> E067 918B B660 DBD1 105C 966C 33F5 F005 6EF4 5358 >> > -- > > --- > 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. > Visit this group at > http://groups.google.com/a/isocpp.org/group/std-proposals/. -- --- You received this message because you are subscribed to the Google Groups "ISO C++ Standard - Future Proposals" group. 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