220 4429 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: Wed, 15 May 2013 11:04:36 -0300 Lines: 271 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=047d7b343baa44fbdb04dcc23d5f X-Trace: ger.gmane.org 1368626719 5621 80.91.229.3 (15 May 2013 14:05:19 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 15 May 2013 14:05:19 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCOPV7FAXQPRBHFMZ2GAKGQEK2ATBZY@isocpp.org Wed May 15 16:05:20 2013 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-fa0-f69.google.com ([209.85.161.69]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1UccKW-0006gA-0e for gclcip-std-proposals@m.gmane.org; Wed, 15 May 2013 16:05:20 +0200 Original-Received: by mail-fa0-f69.google.com with SMTP id a11sf1427347fad.8 for ; Wed, 15 May 2013 07:05:17 -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=26+cxnbfNG4sDE9vuPuh0tE66HwZhmwGWYqfIbsNcJE=; b=r5TN/xSp1le6y74roCWbDDkBs9KzyOSUq+64MuFLoOBP6cUqKQOBC/mQ23o1S2VBnq S8ZBvAE3tZDR4Gvzbot+/q/yRSJJ7uFfpIratL9crOdYXPI1V9eir2FcaEuexaxkYe3E BOPpCCx0eyl2EPNlia4TkfwIAHWeYvG80uMbf7ix35Rw8F27L0fz4mroJOEkwpWbUVqb cxsW+Sxp8y6s5OKIDx8FDieTTm2bzk4hvF6dz9tv0U3/qTeSxq41FR/etCECQ0WShH6L lK4Jyyzs5bv1fgglmwoGBNU7fykUpOgrTpiUCJ4AGdzHIDnWb29iRKs64FPfXdjOM6qO X-Received: by 10.112.140.105 with SMTP id rf9mr11346873lbb.21.1368626717240; Wed, 15 May 2013 07:05:17 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.152.27.230 with SMTP id w6ls52408lag.68.gmail; Wed, 15 May 2013 07:05:16 -0700 (PDT) X-Received: by 10.112.156.133 with SMTP id we5mr17820052lbb.22.1368626716714; Wed, 15 May 2013 07:05:16 -0700 (PDT) Original-Received: from mail-la0-x22a.google.com (mail-la0-x22a.google.com [2a00:1450:4010:c03::22a]) by mx.google.com with ESMTPS id pc8si1106781lbc.188.2013.05.15.07.05.16 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 15 May 2013 07:05:16 -0700 (PDT) Received-SPF: pass (google.com: domain of fernando.cacciola@gmail.com designates 2a00:1450:4010:c03::22a as permitted sender) client-ip=2a00:1450:4010:c03::22a; Original-Received: by mail-la0-f42.google.com with SMTP id er20so1807236lab.15 for ; Wed, 15 May 2013 07:05:16 -0700 (PDT) X-Received: by 10.112.149.8 with SMTP id tw8mr17450925lbb.117.1368626716538; Wed, 15 May 2013 07:05:16 -0700 (PDT) Original-Received: by 10.114.80.164 with HTTP; Wed, 15 May 2013 07:04:36 -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::22a 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:4429 Archived-At: --047d7b343baa44fbdb04dcc23d5f Content-Type: text/plain; charset=ISO-8859-1 On Wed, May 15, 2013 at 10:58 AM, Tony V E wrote: > > > > On Wed, May 15, 2013 at 8:30 AM, Fernando Cacciola < > fernando.cacciola@gmail.com> wrote: > >> On Wed, May 15, 2013 at 9:25 AM, Ville Voutilainen < >> ville.voutilainen@gmail.com> wrote: >> >>> >>> >>> >>> On 15 May 2013 15:20, Fernando Cacciola wrote: >>> >>>> I did a little bit of further homework on the matter. boost::tuple does >>>> NOT synthesize the comparison operators, >>>> >>>>> but rather calls the operator of the underlying type. The existing >>>>> practice isn't consistent. ;) >>>>> >>>>> This needs at least an overview paper. I'd be willing to entertain the >>>>> idea to propose making all relational >>>>> operators, including tuple and containers, to not synthesize. I >>>>> suppose the fallback plans are synthesize-for-all >>>>> and deliberately-inconsistent, not necessarily in any preference order. >>>>> >>>>> In addition to that, tuples and containers would seemingly need >>>>> std::less specializations. That's actually somewhat separate. >>>>> >>>>> Fernando, Tony, would you be interested in coauthoring? >>>>> >>>> >>>> Now that I am much more convinced that the right approach is to not >>>> synthesize (consistently across the whole library), I would definitely like >>>> to coauthor such a paper! >>>> >>>> >>>> >>> For you, and Tony too, I want to include the "fallback" options in the >>> paper. According to what Nevin said, >>> people may already rely on the existing synthesizing, so the outcome is >>> not easy to predict. At a minimum, >>> I'll live with whatever the decision will be, at least we have voiced >>> the concerns with the paper. >>> >>> Agreed. >> >>> > > Since I was planning on writing a paper or two about this anyhow, I will > definitely help. > > I think the best fallback plan is that in the case where T *does not have* > an operator>, the tuple will still generate one, (if T *does* have > that > it is used). So any existing code that wouldn't compile without > synthesizing will still work. (If T had inconsistent operators, they get a > behaviour change due to no longer synthesizing.) > > Makes sense. > But I'd like to consider that a (partial) backwards compatibility hack, > and not have optional support that behaviour. ie I'd rather have optional > > fail to compile if you don't have the underlying operator. > OK. I think this is a good idea in the specific case of optional. I do share the view of others that optional is something of a T more than the other wrappers and containers. > > I'd prefer if as much as possible each issue was a separate paper. > Optional operator> separate from optional std::less. tuple/pair separate > from optional. > Agreed. -- 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. --047d7b343baa44fbdb04dcc23d5f Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
On W= ed, May 15, 2013 at 10:58 AM, Tony V E <tvaneerd@gmail.com>= wrote:

=


On Wed, May 1= 5, 2013 at 8:30 AM, Fernando Cacciola <fernando.cacciola@gmail.c= om> wrote:
=
On Wed, May 15, 2013 at 9:25 AM, Ville Vout= ilainen <ville.voutilainen@gmail.com> wrote:



On 15 May 2013 15:20, Fernando = Cacciola <fernando.cacciola@gmail.com> wrote:
=
I did a little bit of further homework= on the matter. boost::tuple does NOT synthesize the comparison operators,<= br>
=
but rather calls the operator of the underl= ying type. The existing practice isn't consistent. ;)

This needs at least an overview paper. I'd be willing to= entertain the idea to propose making all relational
operators, includin= g tuple and containers, to not synthesize. I suppose the fallback plans are= synthesize-for-all
and deliberately-inconsistent, not necessarily in any preference order.
=
In addition to that, tuples and containers would seemingly = need std::less specializations. That's actually somewhat separate.

Fernando, Tony, would you be intereste= d in coauthoring?

Now that I am much more convinced that the right approach is to not synt= hesize (consistently across the whole library), I would definitely like to = coauthor such a paper!



For = you, and Tony too, I want to include the "fallback" options in th= e paper. According to what Nevin said,
people may already rel= y on the existing synthesizing, so the outcome is not easy to predict. At a= minimum,
I'll live with whatever the decision will be, at least we ha= ve voiced the concerns with the paper.

Agreed.


Si= nce I was planning on writing a paper or two about this anyhow, I will defi= nitely help.

I think the= best fallback plan is that in the case where T *does not have* an operator= >, the tuple will still generate one, (if T *does* have > that it is = used). So any existing code that wouldn't compile without synthesizing = will still work. (If T had inconsistent operators, they get a behaviour cha= nge due to no longer synthesizing.)

Makes sense.=A0
But I'd like to consider that a (parti= al) backwards compatibility hack, and not have optional support that behavi= our. ie I'd rather have optional > fail to compile if you don't = have the underlying operator.

OK. I think this is a good idea in t= he specific case of optional. I do share the view of others that optional i= s something of a T more than the other wrappers and containers.

I'd pre= fer if as much as possible each issue was a separate paper. =A0Optional ope= rator> separate from optional std::less. =A0tuple/pair separate from opt= ional.

Agreed.

=

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

--
 
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Visit this group at http://groups.google.com/a/isocpp.org/group/std-pro= posals/?hl=3Den.
 
 
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