220 4215 article Path: news.gmane.org!not-for-mail From: Nevin Liber Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Fixing Standard Library relational operators (was: Re: optional Rev.4 (N3672): What was the rationale to remove !=, >=, ...) Date: Thu, 2 May 2013 16:19:35 -0500 Lines: 103 Approved: news@gmane.org Message-ID: Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary=00151757716404d22204dbc2cdd6 X-Trace: ger.gmane.org 1367529632 11189 80.91.229.3 (2 May 2013 21:20:32 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 2 May 2013 21:20:32 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCE35H5S6IDBBGFRROGAKGQERWKLMHQ@isocpp.org Thu May 02 23:20:31 2013 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-gh0-f200.google.com ([209.85.160.200]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1UY0vU-0006AV-2a for gclcip-std-proposals@m.gmane.org; Thu, 02 May 2013 23:20:28 +0200 Original-Received: by mail-gh0-f200.google.com with SMTP id 10sf1486311ghy.7 for ; Thu, 02 May 2013 14:20:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=x-received:x-beenthere:x-received:received-spf:x-received :mime-version:sender:from:date:message-id:subject:to :x-original-sender:x-original-authentication-results:reply-to :precedence:mailing-list:list-id:x-google-group-id:list-post :list-help:list-archive:list-subscribe:list-unsubscribe:content-type; bh=LYGSJftZIn/C3/bx9D8tQ/Rbx+nE9ck8LTMjFKkPrv0=; b=MQ7HOfB1xasCLuXlIGqR5Fc/bGKXAczq+cWnRFYU8yygOe+A4KpzjweyY4D4xYpjlV qbU/XnaQaE4qWfjY//iQ5USDLhpifyrxr2teJ5sKsyM/OlhSxTF+k7+SEs/KnhIZJPVi 0Ru4hVfd7jUzyNmMZjEENfyKH1LVgpkSu6PNOdFJpX0P7WJoFcJ7PfvVdIY9/E3+mqCT maOitrUmtA9I3/8+nbIqItlpf5kdx4XS+ME4vFHCelNl2YziK0DdmYXjW2V6nOdE2uTX HsTWd4DugJdUY0Op1Ox6ZQR+s0aoTxGaFnQgdqjt0KtpxYFO0JHhPkIcoLECpWz/ujXj HvMg== X-Received: by 10.236.183.98 with SMTP id p62mr6678040yhm.3.1367529627123; Thu, 02 May 2013 14:20:27 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.49.47.48 with SMTP id a16ls891870qen.25.gmail; Thu, 02 May 2013 14:20:17 -0700 (PDT) X-Received: by 10.229.139.83 with SMTP id d19mr3464647qcu.100.1367529616983; Thu, 02 May 2013 14:20:16 -0700 (PDT) Original-Received: from mail-qe0-f43.google.com (mail-qe0-f43.google.com [209.85.128.43]) by mx.google.com with ESMTPS id t20si2540054qcw.146.2013.05.02.14.20.16 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 02 May 2013 14:20:16 -0700 (PDT) Received-SPF: pass (google.com: domain of nliber@gmail.com designates 209.85.128.43 as permitted sender) client-ip=209.85.128.43; Original-Received: by mail-qe0-f43.google.com with SMTP id 1so550132qec.2 for ; Thu, 02 May 2013 14:20:16 -0700 (PDT) X-Received: by 10.229.61.40 with SMTP id r40mr3423536qch.81.1367529616606; Thu, 02 May 2013 14:20:16 -0700 (PDT) Original-Sender: nliber@gmail.com Original-Received: by 10.49.24.169 with HTTP; Thu, 2 May 2013 14:19:35 -0700 (PDT) X-Original-Sender: nevin@eviloverlord.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of nliber@gmail.com designates 209.85.128.43 as permitted sender) smtp.mail=nliber@gmail.com; dkim=pass header.i=@gmail.com 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:4215 Archived-At: --00151757716404d22204dbc2cdd6 Content-Type: text/plain; charset=ISO-8859-1 On 2 May 2013 16:05, Ville Voutilainen wrote: > > > Precisely. And I want to restore that state, and add a std::less > specialization, and do anything more elaborate > separately, _if at all_. However, regarding std::less, we need to look at > whether we want to do a specialization > of it for pair/tuple too, I guess. tuple will not work right as an > ordered associative container key, if I > understand correctly. > If we are going for consistency and correctness among everything in the standard library, is this correct solution: operator< should be implemented in terms of operator< of the underlying component(s) operator== should be implemented in terms of operator== of the underlying component(s) std::less should be implemented in terms of std::less of the underlying component(s) std::equal_to should be implemented in terms of std::equal_to of the underlying component(s) operator>, operator<=, operator>= should be written in terms of operator< operator!= should be written in terms of operator== std::greater, std::less_equal, std::greater_equal should be written in terms of std::less std::not_equal_to should be written in terms of std::equal_to -- Nevin ":-)" Liber (847) 691-1404 -- --- 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/?hl=en. --00151757716404d22204dbc2cdd6 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On 2 May 2013 16:05, Ville Voutilainen <ville.voutilainen@gmail.= com> wrote:


Precisely. And I want to restore that state, and add a std::less s= pecialization, and do anything more elaborate
separately, _if at all_. H= owever, regarding std::less, we need to look at whether we want to do a spe= cialization
of it for pair/tuple too, I guess. tuple<T*> will not work right as a= n ordered associative container key, if I
understand correctly.

If we are going for consistency an= d correctness among everything in the standard library, is this correct sol= ution:

operator< should be implemented in terms of operator< of the unde= rlying component(s)
operator=3D=3D should be implemented in terms of ope= rator=3D=3D of the underlying component(s)
std::less should be implement= ed in terms of std::less of the underlying component(s)
std::equal_to should be implemented in terms of std::equal_to of the underl= ying component(s)

operator>, operator<=3D, operator>=3D sho= uld be written in terms of operator<
operator!=3D should be written i= n terms of operator=3D=3D
std::greater, std::less_equal, std::greater_equal should be written in term= s of std::less
std::not_equal_to should be written in terms of std::equa= l_to
--
=A0Nevin ":-)" Liber=A0 <mailto:nevin@eviloverlord= ..com>=A0 (847) 691-1404

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