220 27939 article Path: news.gmane.org!.POSTED!not-for-mail From: Derek Ross Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Make (strongly typed) enums castable to char const * const Date: Thu, 25 Aug 2016 08:17:11 -0700 (PDT) Lines: 172 Approved: news@gmane.org Message-ID: References: <1472132849.17129.9.camel@bsdforen.de> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_261_424528993.1472138231816" X-Trace: blaine.gmane.org 1472138240 2080 195.159.176.226 (25 Aug 2016 15:17:20 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Thu, 25 Aug 2016 15:17:20 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBDJJ7WHE3YKRB6EX7S6QKGQEZRVKXUA@isocpp.org Thu Aug 25 17:17:16 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-qk0-f199.google.com ([209.85.220.199]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1bcwP5-00005I-8x for gclcip-std-proposals@m.gmane.org; Thu, 25 Aug 2016 17:17:15 +0200 Original-Received: by mail-qk0-f199.google.com with SMTP id m184sf99773500qkb.2 for ; Thu, 25 Aug 2016 08:17:16 -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 :x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=mN1C+TRugkjgKHGYNqj7J+eke7rWhzhiXHNFFWYgQFw=; b=nlEjMJNyHG7/jStcpufm84CDBaXhNhBk2oqSDxt4vapZ5VIJmhkfUcl/4qt/WDeM/b JN+/ZyGp7CBSIR8EKMsmDdkPr0uIsRavizIaQq22suEaLHpPS3JKWTMiFu5S4jwzwX/J qQEgx8FupCCbBK+YMoU9TqYMwY00TO+UM7twGgzge0CvfrOwEtQA6eYZeqb5ELkwjEnc ZTHSny/FGx6KbhoY5uVX950pT/jvGAQo0ySkn6JLMmxvtd8XQ6v5ljx0uDMp1gripsdH OOvkjgZgQAhy7UV2GT9wo4weSQRcRzsTcuhQF0JKu3sGNWjScvZ1HHbcINXtGvX4DMnA hxrA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=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=mN1C+TRugkjgKHGYNqj7J+eke7rWhzhiXHNFFWYgQFw=; b=WIsZh1dvwTdKz92OcGs880VelOa7P9NLtxsQ8m217R+xqztqfi/C4gNWCGf3xlEfuj PjQVjVE8BD65Fyh/ghfrwQ2XmFjJ6U60ACH6jhtF4QJTBVEXiVNDOhSXgC6LvpZMg9Lo V6oBk2P9g868Y7OA0fn7Dbavl2P2sddlvyZbu+vsHh/ZuHcxWZ9b3XhtfQeRMgG81tqm 6K0/IAYOWeNzeCW6aqMX/wGjGUWMzf0S/rwMaw1dsixGEvZo0OJYasKMzm7SrWppwji1 N7MtHZCy8tw+UCJruXv5n48nQM6MH0C12ZBaZ0ajI/aom9B9ob8eFTnm4B7X0oaJaZwq Hp7Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; 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=mN1C+TRugkjgKHGYNqj7J+eke7rWhzhiXHNFFWYgQFw=; b=XzRJOQXa481n/kn5OxZEMmK+qb93NKjzfkC+pwMJJXJaeno2I1C5rS3PXC7ohNPWjx ejtEeJqPf32JYepD4jGCOUgJBG5hQTpaiPm9JQtRG9vz6SGHjW6NkAjhgSWw7JSmijCn Ve809R7ln5kVtO+deuyC3K/8RSTNqQcqEOp8IyhmE7viYyVvz/xiNGqpKr2nT9yMTCp6 Bvpnuf1m524cXEAJHUnYy+DwVSNSItndzcM67POkxjdqjBITqlNMW2mXN7YHN8mmPdx6 /YoXK1PVk22XSbBtF3nenc/RN3n2g5cxWArjKAEPFc3ut/NFmeju7OloLwGtR4VgWJfs evgA== X-Gm-Message-State: AEkoouuzUTEuNyhi7B5KQAgj1HkhnOPDPL+uqlwK3hmuzpCNMkdZMRtq22hz0hjnUiqXYQ== X-Received: by 10.31.50.72 with SMTP id y69mr6246490vky.13.1472138235937; Thu, 25 Aug 2016 08:17:15 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.107.133.30 with SMTP id h30ls506321iod.20.gmail; Thu, 25 Aug 2016 08:17:12 -0700 (PDT) X-Received: by 10.36.227.207 with SMTP id d198mr240290ith.4.1472138232706; Thu, 25 Aug 2016 08:17:12 -0700 (PDT) In-Reply-To: <1472132849.17129.9.camel@bsdforen.de> X-Original-Sender: antiquarktv@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:27939 Archived-At: ------=_Part_261_424528993.1472138231816 Content-Type: multipart/alternative; boundary="----=_Part_262_1782411998.1472138231816" ------=_Part_262_1782411998.1472138231816 Content-Type: text/plain; charset=UTF-8 Note that enums can have duplicate values, which throws a wrench into the reflection works. E.g.: enum class FooBar { KEKS = 2, DOSE = 2 }; What will the result be for: FooBar fb = FooBar::KEKS; cout << static_cast(fb) ; On Thursday, August 25, 2016 at 8:47:34 AM UTC-5, Kamikaze Dominic Fandrey wrote: > > I searched this list for similar suggestions, but of course I may > have overlooked something. > > I frequently use the following pattern: > > enum class FooBar { KEKS, DOSE }; > char const * const FooBarStr[]{"KEKS", "DOSE"}; > > I use the strings to in error messages, verbose output, etc. > > FooBarStr[static_cast(FooBar::KEKS)] // "KEKS" > > This has some disadvantages, e.g. enums with explicitly stated values > may have gaps, negative values and may be defined out of order. > Also, changing the enum also means changing the strings manually. > > What I'd like to see: > > static_cast(FooBar::KEKS) // "KEKS" > > I think this would be simple to add to an existing compiler and it's > very unlikely to clash with existing code, because you have to jump > through some hoops to cast a strongly typed enum to a pointer type. > > -- > A: Because it fouls the order in which people normally read text. > Q: Why is top-posting such a bad thing? > A: Top-posting. > Q: What is the most annoying thing on usenet and in e-mail? > > > -- 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/e585a9d9-c120-48a9-9ab7-2cbfbc206038%40isocpp.org. ------=_Part_262_1782411998.1472138231816 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Note that enums can have duplicate values, which throws a = wrench into the reflection works.=C2=A0 E.g.:

=
enum class FooBar {= KEKS =3D 2, DOSE =3D 2= };=

What will the result be for:

FooBar fb =3D FooBar::= KEKS;
cout <<<= span style=3D"color: #000;" class=3D"styled-by-prettify"> static_cast<char const*>(fb) ;




On Thursday, August 25, 2016 at 8:47:3= 4 AM UTC-5, Kamikaze Dominic Fandrey wrote:
I searched this list for similar suggestions, but of course I = may
have overlooked something.

I frequently use the following pattern:

=C2=A0 =C2=A0 enum class FooBar { KEKS, DOSE };
=C2=A0 =C2=A0 char const * const FooBarStr[]{"KEKS", "DO= SE"};

I use the strings to in error messages, verbose output, etc.

=C2=A0 =C2=A0 FooBarStr[static_cast<int>(FooBar::KEKS)] // &= quot;KEKS"

This has some disadvantages, e.g. enums with explicitly stated values
may have gaps, negative values and may be defined out of order.
Also, changing the enum also means changing the strings manually.

What I'd like to see:

=C2=A0 =C2=A0 static_cast<char const *>(FooBar::KEKS) // "KE= KS"

I think this would be simple to add to an existing compiler and it'= s
very unlikely to clash with existing code, because you have to jump
through some hoops to cast a strongly typed enum to a pointer type.

--=20
A: Because it fouls the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?


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