220 9933 article Path: news.gmane.org!not-for-mail From: Matheus Izvekov Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Explicitly-defaulted enumeration operators Date: Wed, 19 Mar 2014 16:33:42 -0700 (PDT) Lines: 119 Approved: news@gmane.org Message-ID: References: <3B09C97E-7ADE-49ED-8C31-B5B41CD3DDE7@gmail.com> <781009e3-cd3c-4cb8-b034-b51a7c97c750@isocpp.org> <10450602-fee9-48c4-9fa2-d000e434f5fb@isocpp.org> <6F532E62-C10A-404A-8F0D-662B7EA3D202@gmail.com> <24e85eaf-e67b-4a0b-acee-47d996d6f6ee@isocpp.org> <7F327393-B9EF-46EB-A40E-86F80EFEF5BD@gmail.com> <532A2217.10905@users.sourceforge.net> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_56_2736425.1395272022717" X-Trace: ger.gmane.org 1395272016 18945 80.91.229.3 (19 Mar 2014 23:33:36 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 19 Mar 2014 23:33:36 +0000 (UTC) Cc: matthew.woehlke@kitware.com To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCOKZ27XTMNRBWGSVCMQKGQERM3LLLI@isocpp.org Thu Mar 20 00:33:46 2014 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ig0-f199.google.com ([209.85.213.199]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1WQPzV-0001A1-E0 for gclcip-std-proposals@m.gmane.org; Thu, 20 Mar 2014 00:33:45 +0100 Original-Received: by mail-ig0-f199.google.com with SMTP id uy17sf748394igb.2 for ; Wed, 19 Mar 2014 16:33:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=date:from:to:cc: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:content-type; bh=MwfgSz9LwBbA5ymbttUKwi9Va89m/r6GGHHl6S6UBD8=; b=rSc2V16ciIlDeAjNoqbdjhhummBDmwUg8E194blvR/tNuZYsb79KQN28uCFRM6ZfO0 2qaC+QrlAdqv0qniSEvQdaLM13pBLNsTyx5jdKjE+FwjN1Jora6ixkZ9nb5PWVqjbRp9 6nVDcWNCTHyFAjconK7ghM7J4OOrHPX2BWRc4Y3WzL3czTk3Q7bsgYTjNKGcf/fULX/B lJo0YQ9XVbEdZefuGE4mHDwk7e7CFLWUZwTgq+11pZpPMCyRE50GH/ExKvqmHijM6Yg/ /c7jjfXLSZggNe5SYZnGa5PO4HrlMa0hH67lunoCp+lTWd5nNKScobF5SUMEA87852v7 gcwA== 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:cc: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:content-type; bh=MwfgSz9LwBbA5ymbttUKwi9Va89m/r6GGHHl6S6UBD8=; b=YhktYjDUmSxpU5xuhqeNxzQEmWXSNh7MTTSSRgOU9Z4PMozS9BqFGj5SC8eGWlmE0B JhzrziRLZ3hjoglfszawOrr3vtJ6+XRoAXyHP98dODpLfkFTJTPNpjTtLGiCALANh7oW pfzuJ45twwEN+lZB7b+s+zg2eE7um+9/uD6+TQMIiJqSN9kzhOi9/tJNxJw+FhLvdrfO UMzUGD+g4QijAE/QXGE5qTZ5E9xD6MV/S11iMg03zBCFEzjdJWRRfjQK89NHw6C28H93 U+GsrQZrmnKvu1K2E4fCIS4V0BsfJra+tGz44FxJ0J2r1kaG+X4sKfR+ajU6LlU7X+1Y +4+g== X-Gm-Message-State: ALoCoQlLqyxyNV8zWDAE1XK8gtJcx7BLc/R9TfqlWiAWck1aOouMeg5sBHIeq96jSEgcc5Nvexlk X-Received: by 10.42.53.135 with SMTP id n7mr14927941icg.11.1395272024494; Wed, 19 Mar 2014 16:33:44 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.140.18.175 with SMTP id 44ls19159qgf.24.gmail; Wed, 19 Mar 2014 16:33:43 -0700 (PDT) X-Received: by 10.140.48.235 with SMTP id o98mr765qga.35.1395272023835; Wed, 19 Mar 2014 16:33:43 -0700 (PDT) In-Reply-To: <532A2217.10905@users.sourceforge.net> X-Original-Sender: mizvekov@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:9933 Archived-At: ------=_Part_56_2736425.1395272022717 Content-Type: text/plain; charset=UTF-8 On Wednesday, March 19, 2014 8:02:47 PM UTC-3, Matthew Woehlke wrote: > > (I'm leaving the entirety of Matheus text as something appears to have > eaten that message...) > > It also ate yours. Got them on my email but they don't show up on google groups web interface. > > Heh. I had one originally, and decided to remove it because I'm not sure > of the answer :-). Intuitively I would say "yes", because if all values > of A are also values of B, it makes sense to allow promotion from A to > B, unless such has been explicitly denied. > > It's also kind of the opposite behavior of an enum class deriving from int though, where implicit conversions both ways are disallowed. > > Probably 'int', a) for the reasons you give above, and b) because I do > think multiple inheritance should be allowed. And I would further agree > that obtaining type 'A' from type 'B' should use the same mechanism as > for "true" classes (which among other things would imply that > is_base_of(A, B) => true). > > I think making enums full on class-like has been discussed before, but I can't find where / which thread it was discussed on. But as far as I remember, it came out unfavorably. I am in favor of allowing literal types as enum underlying types, and if you allow full on enum classes like that, then using a literal class type as underlying type could get really hairy. On the other hand, IMHO making enum classes have similar semantics to opaque typedefs seems a lot simpler and fits better, because as they stand right now, they are a lot like an opaque typedef, but unfortunately support just fundamental integers. -- --- 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/. ------=_Part_56_2736425.1395272022717 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
On Wednesday, March 19, 2014 8:02:47 PM UTC-3, Matthew Woe= hlke wrote:
(I'm leaving the en= tirety of Matheus text as something appears to have=20
eaten that message...)


It also ate yours. Got them on my email but they = don't show up on google groups web interface.
 

Heh. I had one originally, and decided t= o remove it because I'm not sure=20
of the answer :-). Intuitively I would say "yes", because if all values= =20
of A are also values of B, it makes sense to allow promotion from A to= =20
B, unless such has been explicitly denied.


It's also kind of the opposite behavior of an enu= m class deriving from int though,
where implicit conversions both ways a= re disallowed.
 

Probably 'int', a) for the reasons you give above, and b) because I do= =20
think multiple inheritance should be allowed. And I would further agree= =20
that obtaining type 'A' from type 'B' should use the same mechanism as= =20
for "true" classes (which among other things would imply that=20
is_base_of(A, B) =3D> true).


I think making enums full on class-like has been = discussed before, but I can't
find where / which thread it was discussed= on.
But as far as I remember, it came out unfavorably.

I am in f= avor of allowing literal types as enum underlying types, and if you allowfull on enum classes like that, then using a literal class type as underl= ying type could get really hairy.

On the other hand, IMHO making enu= m classes have similar semantics to opaque typedefs seems a lot simpler
= and fits better, because as they stand right now, they are a lot like an op= aque typedef, but unfortunately support just fundamental integers.

--

---
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To unsubscribe from this group and stop receiving emails from it, send an e= mail to std-proposa= ls+unsubscribe@isocpp.org.
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