220 19213 <88e7af16-11e2-41a1-85f8-9e70003dff48@isocpp.org> article Path: news.gmane.org!not-for-mail From: Vlad from Moscow Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Overloading std::begin and std::end for std::pair Date: Thu, 23 Jul 2015 12:18:04 -0700 (PDT) Lines: 126 Approved: news@gmane.org Message-ID: <88e7af16-11e2-41a1-85f8-9e70003dff48@isocpp.org> References: <012fd35d-96fd-4775-835e-2105176c4f97@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_759_905092172.1437679084352" X-Trace: ger.gmane.org 1437679087 12835 80.91.229.3 (23 Jul 2015 19:18:07 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 23 Jul 2015 19:18:07 +0000 (UTC) Cc: sean.middleditch@gmail.com To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBCXLLRHD7IDRB3P3YSWQKGQE5HEJJDA@isocpp.org Thu Jul 23 21:18:07 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 1ZIM0M-0000bc-OY for gclcip-std-proposals@m.gmane.org; Thu, 23 Jul 2015 21:18:06 +0200 Original-Received: by qgeu79 with SMTP id u79sf1938555qge.1 for ; Thu, 23 Jul 2015 12:18:05 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:date:from:to:cc:message-id:in-reply-to :references:subject:mime-version:content-type:x-original-sender :reply-to:precedence:mailing-list:list-id:x-spam-checked-in-group :list-post:list-help:list-archive:list-subscribe:list-unsubscribe; bh=HRJchb29oHktEPoB4CTw54iuvpwsywsNyHSIYWw+Zng=; b=hk63ELSsda3zVybP023l8fPIm7ehsy+MKjlKrRG2ZcLq6fGyQ+z2nZYZMZrNYfXo8D dFR3Q6D51HhxgFHxNr9jmn5BwMjXGWlT1uVlZYcRQXk4yUIDpbk0FCG1PyYrfjy1nU2P EpZf9HklZ8PSsgnzakc9sc7I9FiYIqbRDKRW5nNpD8u1DW801c2w25tE1TnFRYQg2X8G cg8vbSSHSLFUWzLZHGZfWCRz7PXZHPyAevRz/E4r0jtEQEFeYa2qF20wMudgD0GMaRkh LXjqUP57e5RdHQ9rU+9+U+FqRBK5A5FBD4aopyafhdTNuca8aOOpaBR0LbqW/ctkgzTF cseg== X-Gm-Message-State: ALoCoQlucznw+AuVei8Gy0vKQ7ACM/8a3C8HluvLrXoEkbIf9HmkmBMH/Amh6gA4lXcyxZKgjcJR X-Received: by 10.13.244.2 with SMTP id d2mr10048452ywf.34.1437679085824; Thu, 23 Jul 2015 12:18:05 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.140.39.84 with SMTP id u78ls1243838qgu.31.gmail; Thu, 23 Jul 2015 12:18:05 -0700 (PDT) X-Received: by 10.140.101.243 with SMTP id u106mr222949qge.27.1437679085084; Thu, 23 Jul 2015 12:18:05 -0700 (PDT) In-Reply-To: X-Original-Sender: vlad.moscow@mail.ru 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:19213 Archived-At: ------=_Part_759_905092172.1437679084352 Content-Type: multipart/alternative; boundary="----=_Part_760_1532103494.1437679084353" ------=_Part_760_1532103494.1437679084353 Content-Type: text/plain; charset=UTF-8 There is nothing solved by ranges. I would prefer to use what I already have that is std::pair. I do not need for such tasks new compound classes as ranges. And as far as I know array_view does not work with for examples std::map. On Thursday, July 23, 2015 at 10:04:27 PM UTC+3, Sean Middleditch wrote: > This is solved by ranges (there's a proposal in flight derived from > https://github.com/ericniebler/range-v3). You're trying to treat > std::pair as a range between the two iterators, which > is not semantically correct for all possible pairs of iterators. I'd rather > just leave pair alone and let the ranges proposal solve this by replacing > the handle of STL uses of pair with a range. > > In your example it's also solved by array_view, which is really just a > form of range. > > An additional nice thing about the ranges is that begin, end, size, > operator[], etc. can all be added to the range type as member functions (as > appropriate for the iterator category). > > On Thursday, July 23, 2015 at 10:36:46 AM UTC-7, Vlad from Moscow wrote: >> >> I'd like to suggest very simple and at the same time very useful >> overloaded functions std::begin and std::end for standard class std::pair. >> >> Here is a demonstrative program of the idea >> >> #include >> #include >> >> namespace std >> { >> template >> Iterator begin( const std::pair &p ) >> { >> return p.first; >> } >> template >> Iterator end( const std::pair &p ) >> { >> return p.second; >> } >> } >> > -- --- You received this message because you are subscribed to the Google Groups "ISO C++ Standard - Future Proposals" group. 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There is nothing solved by ranges. I would prefer to = use what I already have that=C2=A0 is std::pair. I do not need for such tas= ks new compound classes as ranges.

And as far= as I know array_view does not work with for examples std::map.
<= br>On Thursday, July 23, 2015 at 10:04:27 PM UTC+3, Sean Middleditch wrote:=
This is solved by range= s (there's a proposal in flight derived from h= ttps://github.com/ericniebler/range-v3). You're trying to treat std= ::pair<iterator, iterator> as a range between the two iterators, whic= h is not semantically correct for all possible pairs of iterators. I'd = rather just leave pair alone and let the ranges proposal solve this by repl= acing the handle of STL uses of pair<iterator, iterator> with a range= <iterator>.

In your example it's also solved b= y array_view, which is really just a form of range.

= An additional nice thing about the ranges is that begin, end, size, operato= r[], etc. can all be added to the range type as member functions (as approp= riate for the iterator category).

On Thursday, July 23, 2015 at 10:3= 6:46 AM UTC-7, Vlad from Moscow wrote:
I'd like to =C2=A0suggest very simple and=C2=A0at the sam= e time very useful=C2=A0 overloaded functions std::begin and std::end for s= tandard class std::pair.

Here is a demonstrative p= rogram of the idea

#include <iostream>
=
#include <utility>

namespace std
{= =C2=A0=C2=A0=C2=A0
template <class Iterator>
Iterator begin( c= onst std::pair<Iterator, Iterator> &p )
{
=C2=A0=C2=A0=C2= =A0 return p.first;
}
template <class Iterator>
Itera= tor end( const std::pair<Iterator, Iterator> &p )
{
=C2=A0= =C2=A0=C2=A0 return p.second;
}
}

--

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