220 4239 article Path: news.gmane.org!not-for-mail From: Nevin Liber Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Fixing Standard Library relational operators (was: Re: optional Rev.4 (N3672): What was the rationale to remove !=, >=, ...) Date: Fri, 3 May 2013 09:27:13 -0500 Lines: 126 Approved: news@gmane.org Message-ID: References: Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary=047d7bb050824982d904dbd12847 X-Trace: ger.gmane.org 1367591283 11308 80.91.229.3 (3 May 2013 14:28:03 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 3 May 2013 14:28:03 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCE35H5S6IDBB34SR6GAKGQEDA4CH3Y@isocpp.org Fri May 03 16:28:03 2013 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-gg0-f197.google.com ([209.85.161.197]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1UYGxt-0002Ol-DT for gclcip-std-proposals@m.gmane.org; Fri, 03 May 2013 16:28:01 +0200 Original-Received: by mail-gg0-f197.google.com with SMTP id w6sf2435568ggk.8 for ; Fri, 03 May 2013 07:28:00 -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:in-reply-to:references: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=Yvrn3HcuuNlYeAkmW2siI101LptjkHSSGdlFhwHdv5c=; b=IpvpqB9ev5vN8FJdvKGUBU1x0SqbK37iN34j+ISrvRuLVdd9wwGdnaEUuwoyC1eI4c 5AWOAnJ0Gud5X1uRx2f/brFSJGlEDZZk0RzbUiGwm4lro9rlGDobg2quWKB07XNDmd8U Pdu4MS9YWgaHFwJ4aS5f5qRcuJOKMWsf849Abl9gyk7IYSLagL8++h7D2lNW726ZL5lN foBCIVJ6bwa8eze8GLPfGR8vyaal7m7MZNucLAHWM7cNoEtUclp8Z7d0m+tfDvZ5Pt+A pGsNhyjfEa0V0sMqZ0qCASBYsF8B6Nnz2r1Za3dbXtciKyBY5kBrE X-Received: by 10.236.91.109 with SMTP id g73mr8245203yhf.23.1367591280366; Fri, 03 May 2013 07:28:00 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.49.86.232 with SMTP id s8ls1139327qez.94.gmail; Fri, 03 May 2013 07:27:58 -0700 (PDT) X-Received: by 10.49.35.243 with SMTP id l19mr14105434qej.56.1367591278007; Fri, 03 May 2013 07:27:58 -0700 (PDT) Original-Received: from mail-qe0-f49.google.com (mail-qe0-f49.google.com [209.85.128.49]) by mx.google.com with ESMTPS id v12si3367249qct.186.2013.05.03.07.27.57 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Fri, 03 May 2013 07:27:57 -0700 (PDT) Received-SPF: pass (google.com: domain of nliber@gmail.com designates 209.85.128.49 as permitted sender) client-ip=209.85.128.49; Original-Received: by mail-qe0-f49.google.com with SMTP id 7so919516qeb.36 for ; Fri, 03 May 2013 07:27:57 -0700 (PDT) X-Received: by 10.49.50.162 with SMTP id d2mr14263290qeo.17.1367591277386; Fri, 03 May 2013 07:27:57 -0700 (PDT) Original-Sender: nliber@gmail.com Original-Received: by 10.49.24.169 with HTTP; Fri, 3 May 2013 07:27:13 -0700 (PDT) In-Reply-To: X-Original-Sender: nevin@eviloverlord.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of nliber@gmail.com designates 209.85.128.49 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:4239 Archived-At: --047d7bb050824982d904dbd12847 Content-Type: text/plain; charset=ISO-8859-1 On 2 May 2013 16:19, Nevin Liber wrote: > 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 > The other, simpler possibility is to not specialize the arithmetic operations: operator< should be implemented in terms of std::less of the underlying component(s) operator== 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== This may have surprising results for those who, for instance, think operator< and std::less should do different things (the only place in the standard which does this as far as I know is for pointers, and that is only because C doesn't give them a total ordering), but I see that being as insane as NaN. Thoughts? -- 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. --047d7bb050824982d904dbd12847 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On 2 May 2013 16:19, Nevin Liber <nevin@eviloverlord.com> wrote:
operator< should be implemented in terms of operator< of the underlyi= ng component(s)
operator=3D=3D should be= implemented in terms of operator=3D=3D of the underlying component(s)
s= td::less should be implemented in terms of std::less of the underlying comp= onent(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

The other, simpler possi= bility is to not specialize the arithmetic operations:

operator< should be implemented in terms of std::less of the underly= ing component(s)
operator=3D=3D should be implemented in terms of std::e= qual_to of the underlying component(s)

operator>, operator<=3D= , operator>=3D should be written in terms of operator<
operator!=3D should be written in terms of operator=3D=3D

This may h= ave surprising results for those who, for instance, think operator< and = std::less should do different things (the only place in the standard which = does this as far as I know is for pointers, and that is only because C does= n't give them a total ordering), but I see that being as insane as NaN.=

Thoughts?
--
=A0Nevin ":-)" Liber=A0 <mailto:nevin@eviloverlord.com= >=A0 (847) 691-1404

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