220 32850 article Path: news.gmane.org!.POSTED!not-for-mail From: Mingxin Wang Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: std::enum Date: Thu, 22 Jun 2017 20:18:53 -0700 (PDT) Lines: 89 Approved: news@gmane.org Message-ID: 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_204_941194325.1498187933254" X-Trace: blaine.gmane.org 1498187935 12393 195.159.176.226 (23 Jun 2017 03:18:55 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Fri, 23 Jun 2017 03:18:55 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBDNMBNHJWIGBBHMRWLFAKGQEFGP47FA@isocpp.org Fri Jun 23 05:18:51 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-pf0-f198.google.com ([209.85.192.198]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1dOF7S-0002x3-4T for gclcip-std-proposals@m.gmane.org; Fri, 23 Jun 2017 05:18:50 +0200 Original-Received: by mail-pf0-f198.google.com with SMTP id v62sf19022815pfd.10 for ; Thu, 22 Jun 2017 20:18:55 -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=ujy7rLZsfLHB9GzQwBhLKH5xCMtk+H6zO7Yj9b6UKoE=; b=Wpqbb5lKiYqBUlk7F1KvV8luiCuAwGHCcBlP2WWqT++kmRekeOgf53huYQPFTeTe8P mcc4LHEbWo0qKBq8hhcXudjMr1IZzYyVqm42AaRHqoB9mSq+LuLYuwAsQamNUqxzCvhJ NzlFiH2C/m8fjFA5w4UGeC8fRg1h7fjUAfjOkBiZWmr1Dyr/7qD3ozjzEVOrlZGAV7Py MtlhkC38bGYDFaFRuaW+8nKA+N8bLwOaZMun9llZHGgOq+7z1vcx/tsDkN/A6LVh7pAC k8IOKFc7fgN2yUn7X+YqgZaAh0qDsPPranmwcCgeQGLfumHAMRfeKVmrEQZZ03vreRwv UOyA== 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=ujy7rLZsfLHB9GzQwBhLKH5xCMtk+H6zO7Yj9b6UKoE=; b=Lqf/uZvy+29hvRq3Q5EI0ueK2NoVbYm1kxakGfGnlSWEjCeLQkHa1c8E6BtsjL1bln CdfX1OyTKBoTuquzrs87E+Fbq8mDJRWHqyT2yixcNjaLFha9U0b/Fc/COXP9EZPgPmIS 7ndpqxTqho7jWn+Hrt+yVDIA5LpayfamWzAHrk9igDjmoKJKkJRtDfz/xdlsNscAJO0c 1dBgv3h92fnhU+6xpQE6E5PHNeX3qXD8aZYAW/+CO6bVebROUM1mMSh9OYvIQKNZyVCZ VwniSwVxL4guIsjFotzuH3SwXtN4Qbi6W1bYb19gu0K9QHgtmNLd6sFfHQTntpTmvZVW xe+A== X-Gm-Message-State: AKS2vOzXwGcYxU8c6N645ogjY1Sh6vSZ5ieknb3UIYus3NKHXfjdGQjX 9za/u1Y37pKGTGTz X-Received: by 10.99.186.77 with SMTP id l13mr727646pgu.66.1498187934838; Thu, 22 Jun 2017 20:18:54 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.157.15.189 with SMTP id d58ls7561852otd.25.gmail; Thu, 22 Jun 2017 20:18:53 -0700 (PDT) X-Received: by 10.157.12.161 with SMTP id b30mr151568otb.3.1498187933852; Thu, 22 Jun 2017 20:18:53 -0700 (PDT) In-Reply-To: <1cdd0fbf-c65d-4034-82d1-a84d4c4f6d1c@isocpp.org> X-Original-Sender: wmx16835vv@163.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:32850 Archived-At: ------=_Part_204_941194325.1498187933254 Content-Type: multipart/alternative; boundary="----=_Part_205_1179142056.1498187933254" ------=_Part_205_1179142056.1498187933254 Content-Type: text/plain; charset="UTF-8" On Wednesday, June 21, 2017 at 11:34:28 AM UTC+8, Halfdan Ingvarsson wrote: > > I'd like to propose a simple, but very useful utility class for the > standard library: std::enum. > > 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 declaration, using a nearly identical interface as std::array<> > (i.e either through enumerators, or operator[]). > > Because this depends on new language features, I think the motivation in converting a "enum" to an array is not explicit enough. As a user to the enum, I usually care "the mapping between names and values" more than "the order of declaration". Would it be more reasonable to convert an enum to an initializer list? For example: enum E { ZERO = 0, ONE = 1, TWO = 2 }; std::map a = MAKE_MAP(E); // MALE_MAP(E) is equivalent to {{"ZERO", 0}, {"ONE", 1}, {"TWO", 2}} Still, I think there should be more motivation. As I can imagine, this feature is helpful in debugging and exception information generation. Mingxin Wang -- 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. To view this discussion on the web visit https://groups.google.com/a/isocpp.org/d/msgid/std-proposals/ec30b779-62be-4bf6-aa93-51e281e93811%40isocpp.org. ------=_Part_205_1179142056.1498187933254 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
On Wednesday, June 21, 2017 at 11:34:28 AM UTC+8, Halfdan = Ingvarsson wrote:
I'd like to propose a simple, but very useful utility class for the= standard library: std::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, i= n order of declaration, using a nearly identical interface as std::array<= ;> (i.e either through enumerators, or operator[]).

<= /div>
Because this depends on new language fea= tures, I think the motivation in converting a "enum" to an array = is not explicit enough.

As a user to the enum, I u= sually care "the mapping between names and values" more than &quo= t;the order of declaration". Would it be more reasonable to convert an= enum to an initializer list? For example:

enum E {= ZERO =3D 0, ONE =3D 1, TWO =3D 2 };
std= ::map<std::string, int> a =3D MAKE_MAP(E); // MALE_MAP(E) is equivale= nt to {{"ZERO", 0}, {"ONE", 1}, {"TWO", 2}}

Still, I think there should be more motivation. = As I can imagine, this feature is helpful in debugging and exception inform= ation generation.

Mingxin Wang

--
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/ec30b779-62be-4bf6-aa93-51e281e93811= %40isocpp.org.
------=_Part_205_1179142056.1498187933254-- ------=_Part_204_941194325.1498187933254-- .