220 32822 <546143ae-5acd-4a0e-abde-4f712c51ca30@isocpp.org> article Path: news.gmane.org!.POSTED!not-for-mail From: wei zhang Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: std::enum Date: Tue, 20 Jun 2017 21:12:43 -0700 (PDT) Lines: 223 Approved: news@gmane.org Message-ID: <546143ae-5acd-4a0e-abde-4f712c51ca30@isocpp.org> References: <1cdd0fbf-c65d-4034-82d1-a84d4c4f6d1c@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_1805_1313231126.1498018363948" X-Trace: blaine.gmane.org 1498018365 9515 195.159.176.226 (21 Jun 2017 04:12:45 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Wed, 21 Jun 2017 04:12:45 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBDWIFSHO6EDBBPHEU7FAKGQEUHIURDY@isocpp.org Wed Jun 21 06:12:41 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-it0-f70.google.com ([209.85.214.70]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1dNX0S-0002BD-4k for gclcip-std-proposals@m.gmane.org; Wed, 21 Jun 2017 06:12:40 +0200 Original-Received: by mail-it0-f70.google.com with SMTP id i71sf90996420itf.2 for ; Tue, 20 Jun 2017 21:12:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:message-id:in-reply-to:references:subject:mime-version :x-original-sender:reply-to:precedence:mailing-list:list-id :list-post:list-help:list-archive:list-subscribe:list-unsubscribe; bh=oEAWCPbrucaXtzCM29ZLs7mMuDIY5tA00Hb7HK1qewo=; b=F0OSyuUmCoa4SIldOcTWhu7AVfbHv5zhxC7YS6ArJDZ2LDGqUNveXkCy3K+xRiA2NJ 9++cAxu7xZO5+GOfa/ynvcHsg8LeA9XvPmZzQEv/3gOTlSMnswv09Eo4QQxkgnBmJM0Y RZiU0VmY7fM4+4NeC1wIfsrKej2NhYtQJVxC8J1raQqASUP4TsyJt0OLBPaavKhLIfA9 +LJf97rsnvmgHWk4+gtrOsvAvCfISkSr/YJECl3iVpRd5wCL5/pq+zLqglH2PMaEny4S +wnp2ytu0LO4VmYWowehiv2ijoHfYKgg6oQCCdB3maI7YcKcEseOCmU7BS1NswFmnyu0 ja7g== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:message-id:in-reply-to:references:subject:mime-version :x-original-sender:reply-to:precedence:mailing-list:list-id :list-post:list-help:list-archive:list-subscribe:list-unsubscribe; bh=oEAWCPbrucaXtzCM29ZLs7mMuDIY5tA00Hb7HK1qewo=; b=eD0VPZomHTO54TAcbdHs/AlAI62/41mY2ZcAjkLBzPt9YF8sDZTX+HsMf7SWBeeEYR rjRnSQCHP2zjLYgm47O7JyyNBbZR5b04BQw0f0asKGqx4Cje5XY7ALeEGv+JqsdDp547 ixi+20urUOopMN2IodutHN2u9IcFZTne3W/3x0gaUVewt42ahOwcezk+0TuKIZP8ozLJ I8CP+N1jPddTBwn6KvQzsuFPRkBwoXWgIeWxgZbaO809B3+FWRqcOEInD9PtZymoqamU mYc0zemaFr2fogMVlELNPkqSFHYqrq2wGkX7fWCPgEPuqqr0EGi7e+3/QzEiAAqgugcD tVvw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:message-id:in-reply-to:references :subject:mime-version:x-original-sender:reply-to:precedence :mailing-list:list-id:x-spam-checked-in-group:list-post:list-help :list-archive:list-subscribe:list-unsubscribe; bh=oEAWCPbrucaXtzCM29ZLs7mMuDIY5tA00Hb7HK1qewo=; b=Wmp+7pLpf7wq/WcGWPEwjuGoBTwFUFodlJEMv3BXXeoILto8ekWrD760mIEqxrBjFm 82wWVbe59/CW9d1WsW8Ej8gX49bK8oM/4AQLgtys4Otbj/0uONlEPvPtPj16JNWSK2VG 5q8pyywBh4Jaq6okg+/9A/eNf9JXGcgNDx5pXiysE0k5KzXyrUlW/nF0f0XNeHqhJJun iRIV5ioMWerSL0+z5dUxXyjjIw5nXAIF0U7okQKRKo8PS4pv+LmfG6kA+R8nyTX1Sxbo GNm7K1EkpCvAwfROduSFqbYoydqJeLSqE8RphIJNEobzA/n+H0XXV2cJUV9GEVQSAT1z aIww== X-Gm-Message-State: AKS2vOxz+KnjlNAkCb9xigj32XSMm0d9XyaxP6o9WSH25/qgDekfQO6I b2J0kjs1zwBN0IVR X-Received: by 10.107.205.4 with SMTP id d4mr13535858iog.22.1498018365144; Tue, 20 Jun 2017 21:12:45 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.157.24.23 with SMTP id b23ls2329334ote.7.gmail; Tue, 20 Jun 2017 21:12:44 -0700 (PDT) X-Received: by 10.157.52.161 with SMTP id g30mr625730otc.17.1498018364419; Tue, 20 Jun 2017 21:12:44 -0700 (PDT) In-Reply-To: <1cdd0fbf-c65d-4034-82d1-a84d4c4f6d1c@isocpp.org> X-Original-Sender: lala.willzhang@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:32822 Archived-At: ------=_Part_1805_1313231126.1498018363948 Content-Type: multipart/alternative; boundary="----=_Part_1806_864230015.1498018363949" ------=_Part_1806_864230015.1498018363949 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable I won't think it can be done with only add lib. For the samething I would suggest enum class will have a static const=20 variable array. so that you could write const auto & e =3DColor.array =E5=9C=A8 2017=E5=B9=B46=E6=9C=8821=E6=97=A5=E6=98=9F=E6=9C=9F=E4=B8=89 UTC= +8=E4=B8=8A=E5=8D=8811:34:28=EF=BC=8CHalfdan Ingvarsson=E5=86=99=E9=81=93= =EF=BC=9A > > I'd like to propose a simple, but very useful utility class for the=20 > standard library: std::enum. =20 > > All it does is take a template parameter, which would be an enum type. > > It would then allow you to access the individual elements of that enum, i= n=20 > order of declaration, using a nearly identical interface as std::array<>= =20 > (i.e either through enumerators, or operator[]). > > E.g:=20 > > #include > #include > #include > > > enum Color { Red =3D 1, Green =3D 2, Blue =3D 23 }; > > > int main() > { > auto e =3D std::enum(); > for( auto v: e) > { > std::cout << "Elem: " << v << "\n"; > } > std::cout << "Size: " << e.size() << "\n"; > std::cout << "Largest: " << std::max_element(e.begin(), e.end()) <<=20 > "\n"; > return 0; > } > > Output: > Elem: 1 > Elem: 2 > Elem: 23 > Size: 3 > Largest: 23 > > I assume that this would have to take some form of a help from the=20 > compiler, similar to how std::underlying_type is implemented. However, th= is=20 > would obviate the current set of hacks that either require macros, specia= l=20 > class constructions, or other inconvenient forms. > > --=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/546143ae-5acd-4a0e-abde-4f712c51ca30%40isocpp.or= g. ------=_Part_1806_864230015.1498018363949 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
I won't think it can be done with only add lib.
Fo= r the samething I would suggest enum class will have a static const variabl= e array.
so that you could write
=
const auto & e =3DColor.array




=E5=9C=A8 2= 017=E5=B9=B46=E6=9C=8821=E6=97=A5=E6=98=9F=E6=9C=9F=E4=B8=89 UTC+8=E4=B8=8A= =E5=8D=8811:34:28=EF=BC=8CHalfdan Ingvarsson=E5=86=99=E9=81=93=EF=BC=9A
I'd like to p= ropose a simple, but very useful utility class for the standard library: st= d::enum. =C2=A0

All it does is take a template parameter= , which would be an enum type.

It would then allow= you to access the individual elements of that enum, in order of declaratio= n, using a nearly identical interface as std::array<> (i.e either thr= ough enumerators, or operator[]).

E.g:=C2=A0<= /div>

#include <iostream>
#include<= span style=3D"color:#000"> <enum>
#incl= ude <= ;algorithm>


enum Color { Red =3D 1,= Green = =3D 2,<= span style=3D"color:#000"> Blue =3D 23 };


int main()
{
=C2=A0 =C2=A0auto<= /span> e =3D std::enum<Color>= ();
=C2=A0 =C2=A0for( auto v: e)=
=C2=A0 =C2=A0{
=C2=A0 =C2=A0 =C2=A0std::<= /span>cout <= ;< &= quot;Elem: " << v << "\n";<= span style=3D"color:#000">
=C2=A0 =C2=A0}
=C2=A0 =C2=A0std::cout << "Size: " << e<= /span>.size() = << "\n";
=C2=A0 =C2=A0std::cout << "Largest: " <= /span><<= std::m= ax_element(e.b= egin(),= e.end<= /span>()) << "\n";
=C2=A0 =C2=A0return 0;
}

Output:
Elem: <= span style=3D"color:#066">1
Elem: 2
Elem: 23
Size: 3
Largest: 23
=
I assume that this would have to take some form of a = help from the compiler, similar to how std::underlying_type is implemented.= However, this would obviate the current set of hacks that either require m= acros, special class constructions, or other inconvenient forms.

--
You received this message because you are subscribed to the Google Groups &= quot;ISO C++ Standard - Future Proposals" group.
To unsubscribe from this group and stop receiving emails from it, send an e= mail to std-proposa= ls+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/546143ae-5acd-4a0e-abde-4f712c51ca30= %40isocpp.org.
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