220 34470 <057ee7d2-f5e9-4255-9497-fbf8b64c55f5@isocpp.org> article Path: news.gmane.org!.POSTED!not-for-mail From: inkwizytoryankes@gmail.com Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Musings on customization points, ADL, and the loss of namespaces Date: Sun, 24 Sep 2017 02:19:21 -0700 (PDT) Lines: 188 Approved: news@gmane.org Message-ID: <057ee7d2-f5e9-4255-9497-fbf8b64c55f5@isocpp.org> References: Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_4311_1590037433.1506244761673" X-Trace: blaine.gmane.org 1506244765 6684 195.159.176.226 (24 Sep 2017 09:19:25 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sun, 24 Sep 2017 09:19:25 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBDDLTAGNTIBBBGXRTXHAKGQEOQ6LDFQ@isocpp.org Sun Sep 24 11:19:20 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ua0-f200.google.com ([209.85.217.200]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1dw34G-00015k-Lk for gclcip-std-proposals@m.gmane.org; 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Sun, 24 Sep 2017 02:19:23 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.31.114.203 with SMTP id n194ls3812094vkc.0.gmail; Sun, 24 Sep 2017 02:19:22 -0700 (PDT) X-Received: by 10.31.180.22 with SMTP id d22mr148452vkf.4.1506244762445; Sun, 24 Sep 2017 02:19:22 -0700 (PDT) In-Reply-To: X-Original-Sender: inkwizytoryankes@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:34470 Archived-At: ------=_Part_4311_1590037433.1506244761673 Content-Type: multipart/alternative; boundary="----=_Part_4312_1939803881.1506244761673" ------=_Part_4312_1939803881.1506244761673 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Saturday, September 23, 2017 at 11:54:12 PM UTC+2, Aar=C3=B3n Bueno Vill= ares=20 wrote: > > > Anyway, the solution I purposed was just to add and extra parameter of=20 > type, std::tag, for example, or std::customize inheriting from std::tag= =20 > (imitating the phylosophy of std::exception and its hierarchy), to make t= he=20 > source namespace present as a last user's customization point parameter= =20 > (which will remove the need of "poison pills" too). > > I think this is interesting solution, nobody will by mistaken using this= =20 tag and name conflict will be fix by overloads: namespace std { class customize_t {} customize; template void swap(customize_t, T a, T b); template void swap(T a, T b) { swap(customize, a, b); } } namespace My { class A; void swap(A, A); //backward compatible version for C++03 code void swap(std::customize_t, A a, A b); //new customization point } --=20 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 e= mail to std-proposals+unsubscribe@isocpp.org. To post to this group, send email to std-proposals@isocpp.org. To view this discussion on the web visit https://groups.google.com/a/isocpp= ..org/d/msgid/std-proposals/057ee7d2-f5e9-4255-9497-fbf8b64c55f5%40isocpp.or= g. ------=_Part_4312_1939803881.1506244761673 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable


On Saturday, September 23, 2017 at 11:54:12 PM UTC= +2, Aar=C3=B3n Bueno Villares wrote:

Anyway, the solution I purposed was just to= add and extra parameter of type, std::tag, for example, or std::customize = inheriting from std::tag (imitating the phylosophy of std::exception and it= s hierarchy), to make the source namespace present as a last user's cus= tomization point parameter (which will remove the need of "poison pill= s" too).

I think this is interesting = solution, nobody will by mistaken using this tag and name conflict will be = fix by overloads:
namespace std
{

class customize_t {} cus= tomize;

template= <typename T>
void swap(customize_t, T a, T b);

template<typename T>
void swap(T= a,= T b)
{
=C2=A0 =C2=A0 swap(customize, a, b);
<= span style=3D"color: #660;" class=3D"styled-by-prettify">}


}

namespace My
{
=
class<= /span> A;
void swap(A, A); //backward compatible = version for C++03 code
void= swap(std::customize_t, A a, A b); //new customization point

}


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