220 30203 <6951935.9LYeBEmE6C@tjmaciei-mobl1> article Path: news.gmane.org!.POSTED!not-for-mail From: Thiago Macieira Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: enum_cast proposal Date: Tue, 03 Jan 2017 21:14:56 -0200 Lines: 36 Approved: news@gmane.org Message-ID: <6951935.9LYeBEmE6C@tjmaciei-mobl1> References: <2225413.PkzHcSPZVx@tjmaciei-mobl1> <7d89ec43-c691-44d8-bcb5-74dcda9eb493@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Trace: blaine.gmane.org 1483485313 24529 195.159.176.226 (3 Jan 2017 23:15:13 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Tue, 3 Jan 2017 23:15:13 +0000 (UTC) User-Agent: KMail/5.3.3 (Linux/4.8.13-1-default; KDE/5.28.0; x86_64; ; ) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCB4TK757YBRB5PAWDBQKGQEQF7BYTY@isocpp.org Wed Jan 04 00:15:03 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-lf0-f70.google.com ([209.85.215.70]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1cOYID-0004Vs-P2 for gclcip-std-proposals@m.gmane.org; Wed, 04 Jan 2017 00:14:57 +0100 Original-Received: by mail-lf0-f70.google.com with SMTP id l68sf185060477lfb.1 for ; Tue, 03 Jan 2017 15:15:01 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=from:to:subject:date:message-id:user-agent:in-reply-to:references :mime-version:content-transfer-encoding:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=4VOCZBsnSmMeZ+p2kQg6DlpCTeSTgoc5kxh4K6z9u68=; b=uXNzP6uHNsgtNyjV3MVYRwJbQXWSAvwBZEHgA85jGE5LbaPPs7XE1C5eTNP60jO7AK lnGVvs16x1Z0mvl5SF0YpReVYpLBYU9hHgIRmxxXbzxc9qIoRMoVHW7lfHpIP8eFs/Y3 JlNFWknEGNgjdLb6/Iu+pFoaNEEljENuFYgtJpQqD9lYn0F7hTrVWEOULH5EMXoZ2hZ/ s2VkdfeTZzdvJsqvgmkYoE4+5+cCCKV530XGRNnk3MrH7Lpri47DnzrtKvYJha2OtLM8 b/swOJRcZhM4X/hpgKQmhdxr3WArcz0B4R+zdFds/2F7C2VANdaK17/sPCoTKc/JVlAk X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:subject:date:message-id:user-agent :in-reply-to:references:mime-version:content-transfer-encoding :x-original-sender:x-original-authentication-results:reply-to :precedence:mailing-list:list-id:x-spam-checked-in-group:list-post :list-help:list-archive:list-subscribe:list-unsubscribe; bh=4VOCZBsnSmMeZ+p2kQg6DlpCTeSTgoc5kxh4K6z9u68=; b=ZCo0cC8nPJAk7+m3L5mTA/da6lm794OQAGTCJagIBwN0U3UyFDiFH3LXhunefZt+oR GM0qviRYLV89FTk6qDWtZfudVIaZ2IJ0irvBAma8Go2y7X6w6RnKDlmWBo49inWlIhJh gFVfbbkKWruhbA0Epyts3qVyJ2pxoCs4wRuwNkAN47S8js8EpAsM5VnTpUBjig9ZY+Xn cmkBsm0wo8zQ8j8/Wz6Zh7ZphyRUxOSddwl/jPUKVXrtwmJr+FurK6MZ/C94kmrfOp24 w9jFWVPMUbEtwy5ADLyhtj6o8zHG3fbmk8F/8lVRuk2qRMdQwErGuIVCnEKhUqSgQtGp X-Gm-Message-State: AIkVDXIrOKTlcTfVJy39HU2SDdWWU/7GQfF41ghCBT8wPztXwkYR3grdmjZpZWjDhNQEmQ== X-Received: by 10.25.89.83 with SMTP id n80mr2367514lfb.0.1483485301738; Tue, 03 Jan 2017 15:15:01 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.28.93.209 with SMTP id r200ls3746355wmb.16.canary-gmail; Tue, 03 Jan 2017 15:15:00 -0800 (PST) X-Received: by 10.28.46.144 with SMTP id u138mr50984566wmu.136.1483485300814; Tue, 03 Jan 2017 15:15:00 -0800 (PST) Original-Received: from gondolin.macieira.info (gondolin.macieira.info. [2a01:4f8:d13:f81:21c:14ff:fe01:12a3]) by mx.google.com with ESMTP id y4si79021267wjc.180.2017.01.03.15.15.00 for ; Tue, 03 Jan 2017 15:15:00 -0800 (PST) Received-SPF: pass (google.com: domain of thiago@macieira.org designates 2a01:4f8:d13:f81:21c:14ff:fe01:12a3 as permitted sender) client-ip=2a01:4f8:d13:f81:21c:14ff:fe01:12a3; Original-Received: from tjmaciei-mobl1.localnet (unknown [187.34.234.250]) by gondolin.macieira.info (Postfix) with ESMTPSA id D978711B804 for ; Tue, 3 Jan 2017 15:14:58 -0800 (PST) In-Reply-To: <7d89ec43-c691-44d8-bcb5-74dcda9eb493@isocpp.org> X-Original-Sender: thiago@macieira.org X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of thiago@macieira.org designates 2a01:4f8:d13:f81:21c:14ff:fe01:12a3 as permitted sender) smtp.mailfrom=thiago@macieira.org 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:30203 Archived-At: On ter=C3=A7a-feira, 3 de janeiro de 2017 11:59:46 BRST Nicol Bolas wrote: > Lastly, having `enum_cast` work via some compiler-defined type is rather > extreme for something as simplistic as this, don't you think? There are > only so many ways to implement an "optional", and you can define implicit > conversions from `std::optional` type to yours with little penalty. The > conversion can even be `constexpr`, just like `std::optional`, so you wou= ld > suffer no loss of performance in constexpr contexts. Anything that is a compiler feature (a builtin or a core language expressio= n)=20 needs to be able to choose between std::optional, std::experimental::option= al=20 and std::__1::optional by just changing #includes. A library solution needs not. It seems to me that a library solution wrapping a compiler builtin intrinsi= c=20 is the only solution possible. And using reflection actually matches that= =20 requirement, albeit indirectly. --=20 Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org Software Architect - Intel Open Source Technology Center --=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/6951935.9LYeBEmE6C%40tjmaciei-mobl1. .