220 4428 article Path: news.gmane.org!not-for-mail From: Tony V E 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 09:58:39 -0400 Lines: 204 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=047d7b3432b89ea7e904dcc22553 X-Trace: ger.gmane.org 1368626322 1425 80.91.229.3 (15 May 2013 13:58:42 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 15 May 2013 13:58:42 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCUZ5QWKNQIJDKOORQCRUBALGPWYS@isocpp.org Wed May 15 15:58:42 2013 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-we0-f199.google.com ([74.125.82.199]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1UccE6-0001Nz-A1 for gclcip-std-proposals@m.gmane.org; Wed, 15 May 2013 15:58:42 +0200 Original-Received: by mail-we0-f199.google.com with SMTP id p59sf382625wes.2 for ; Wed, 15 May 2013 06:58:42 -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:mime-version :x-received:in-reply-to:references:date:message-id:subject:from: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=Zk4dXtkaHRkkDuKK66AQGXLCF9xWSWHxu+UOcoxRYmc=; b=UWUNfe1+qa3LdarUJVneaAFSNYEetO40Wz+3D+cWv6JbyNUhLUUxVgegF0En92zs8C JjnCJUjyvrsElhR4fOKo0Zh885qIZd7smKTX8km4cSQ8kOvAkMB4BJl1weahI1oHHkPv uJ6t2y1bVVzGIFnvRuO0gz309diGaA8XNALCYNMz/XBEGh8vpXhG3s0ZjWWhFT+KVg3r DTbuxp5eFS1HG+9RroOpz2FBM67LzdKwM31IsaRKfYGd23oI0rfXk/qI0p9iAi382RSv GcLMPdEu/hi4u+xfoInJzoczSJfpe2QfcL3e8KX/pGxtR7wd0lhJiuuqOgrpfT1XYiur X-Received: by 10.112.180.197 with SMTP id dq5mr11355998lbc.14.1368626321502; Wed, 15 May 2013 06:58:41 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.152.6.39 with SMTP id x7ls55255lax.14.gmail; Wed, 15 May 2013 06:58:40 -0700 (PDT) X-Received: by 10.152.120.40 with SMTP id kz8mr18034964lab.30.1368626320129; Wed, 15 May 2013 06:58:40 -0700 (PDT) Original-Received: from mail-la0-x234.google.com (mail-la0-x234.google.com [2a00:1450:4010:c03::234]) by mx.google.com with ESMTPS id u6si1120312lbu.10.2013.05.15.06.58.40 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 15 May 2013 06:58:40 -0700 (PDT) Received-SPF: pass (google.com: domain of tvaneerd@gmail.com designates 2a00:1450:4010:c03::234 as permitted sender) client-ip=2a00:1450:4010:c03::234; Original-Received: by mail-la0-f52.google.com with SMTP id fo13so1800491lab.11 for ; Wed, 15 May 2013 06:58:40 -0700 (PDT) X-Received: by 10.112.145.72 with SMTP id ss8mr17899809lbb.12.1368626319761; Wed, 15 May 2013 06:58:39 -0700 (PDT) Original-Received: by 10.112.143.37 with HTTP; Wed, 15 May 2013 06:58:39 -0700 (PDT) In-Reply-To: X-Original-Sender: tvaneerd@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of tvaneerd@gmail.com designates 2a00:1450:4010:c03::234 as permitted sender) smtp.mail=tvaneerd@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:4428 Archived-At: --047d7b3432b89ea7e904dcc22553 Content-Type: text/plain; charset=ISO-8859-1 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.) 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. 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. Tony -- --- 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. --047d7b3432b89ea7e904dcc22553 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable



On Wed, May 15, 2013 at 8:30 AM, Fernando Cacciola <fern= ando.cacciola@gmail.com> wrote:
=
On Wed, May 15, 2013 at 9:25 A= M, Ville Voutilainen <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.


Since I was pl= anning 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 cha= nge due to no longer synthesizing.)

But I'd= like to consider that a (partial) backwards compatibility hack, and not ha= ve optional support that behaviour. ie I'd rather have optional > fa= il to compile if you don't have the underlying operator.

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.

Tony<= /div>

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