220 4217 article Path: news.gmane.org!not-for-mail From: Fernando Cacciola 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: Thu, 2 May 2013 18:24:51 -0300 Lines: 139 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=001a11c33e24c3b1eb04dbc2dfb6 X-Trace: ger.gmane.org 1367529934 14522 80.91.229.3 (2 May 2013 21:25:34 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 2 May 2013 21:25:34 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCOPV7FAXQPRBTFTROGAKGQEN6HFG6I@isocpp.org Thu May 02 23:25:35 2013 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-lb0-f199.google.com ([209.85.217.199]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1UY10P-0002O8-NG for gclcip-std-proposals@m.gmane.org; Thu, 02 May 2013 23:25:33 +0200 Original-Received: by mail-lb0-f199.google.com with SMTP id t11sf1531302lbd.2 for ; Thu, 02 May 2013 14:25:33 -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: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=h5pfI3hK5bPEuSDplcJ/B8hUa8Xyiw8080Z5kf1WTgM=; b=nkxLGE61Z8tBZtBmulcExuat/PsZmg0pAhGX+IoSQaMCrrzlhmGhH1PTRJLH2yHPxj qWHHGJv9O98Bujf72YuS3w/D5XCpYYF28RFbwhpqq+cSi0tkCrFd7AjZxb+JejdcWVGF 8AfuYhwrh/m9IzlqGnHAADHIGTuCKgY2O42Qn11tKT6KCy51/LnGVTO2fXhg3jGjTOsV N7BWSwIiBUOAKLfHsswBzF//glCXpw0nsI1vNeXCNVoATRkW6PgtIh7aIyGgtq1HvJBf p2COH3Xr8T8kXuEHWrPiNAcP5XaTL5eIX/JpQJHSpOn1IcCJ7wPQsQOZ78B+cSZqoTF4 X-Received: by 10.152.6.69 with SMTP id y5mr8580138lay.1.1367529933128; Thu, 02 May 2013 14:25:33 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.152.19.232 with SMTP id i8ls150032lae.60.gmail; Thu, 02 May 2013 14:25:31 -0700 (PDT) X-Received: by 10.112.146.34 with SMTP id sz2mr3304028lbb.4.1367529931301; Thu, 02 May 2013 14:25:31 -0700 (PDT) Original-Received: from mail-la0-x22b.google.com (mail-la0-x22b.google.com [2a00:1450:4010:c03::22b]) by mx.google.com with ESMTPS id l3si1267615lag.21.2013.05.02.14.25.31 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 02 May 2013 14:25:31 -0700 (PDT) Received-SPF: pass (google.com: domain of fernando.cacciola@gmail.com designates 2a00:1450:4010:c03::22b as permitted sender) client-ip=2a00:1450:4010:c03::22b; Original-Received: by mail-la0-f43.google.com with SMTP id ea20so976961lab.30 for ; Thu, 02 May 2013 14:25:31 -0700 (PDT) X-Received: by 10.112.72.97 with SMTP id c1mr3319200lbv.96.1367529931123; Thu, 02 May 2013 14:25:31 -0700 (PDT) Original-Received: by 10.114.20.106 with HTTP; Thu, 2 May 2013 14:24:51 -0700 (PDT) In-Reply-To: X-Original-Sender: fernando.cacciola@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of fernando.cacciola@gmail.com designates 2a00:1450:4010:c03::22b as permitted sender) smtp.mail=fernando.cacciola@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:4217 Archived-At: --001a11c33e24c3b1eb04dbc2dfb6 Content-Type: text/plain; charset=ISO-8859-1 On Thu, May 2, 2013 at 6:19 PM, Nevin Liber wrote: > 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 > Actually, if we are going to fix the *entire* library, then we *could* chose to have all operators boild down to the underlying component(s) IIRC, the main reason for not doing so is consistency across the SCL. -- Fernando Cacciola SciSoft Consulting, Founder http://www.scisoft-consulting.com -- --- 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. --001a11c33e24c3b1eb04dbc2dfb6 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
On T= hu, May 2, 2013 at 6:19 PM, Nevin Liber <nevin@eviloverlord.com&g= t; wrote:
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

Actually, if we are going to fix the= *entire* library, then we *could* chose to have all operators boild down t= o the underlying component(s)

IIRC, the main reason for n= ot doing so is consistency across the SCL.

=A0

--
Fernando Cacciol= a
SciSoft Consulting, Founder
http://www.scisoft-consulting.com

--
 
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