220 13939 article Path: news.gmane.org!not-for-mail From: Nevin Liber Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Reconstruct function idea Date: Wed, 15 Oct 2014 16:47:29 -0500 Lines: 68 Approved: news@gmane.org Message-ID: References: <8a74f08b-7453-4d1a-9f20-bc1d3866617c@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary=f46d043890877e47c305057d168b X-Trace: ger.gmane.org 1413409699 2947 80.91.229.3 (15 Oct 2014 21:48:19 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 15 Oct 2014 21:48:19 +0000 (UTC) To: "std-proposals@isocpp.org" Original-X-From: std-proposals+bncBCE35H5S6IDBBGWX7OQQKGQEWO2F6OQ@isocpp.org Wed Oct 15 23:48:13 2014 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-lb0-f197.google.com ([209.85.217.197]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1XeWQV-0002pC-J3 for gclcip-std-proposals@m.gmane.org; Wed, 15 Oct 2014 23:48:11 +0200 Original-Received: by mail-lb0-f197.google.com with SMTP id p9sf1199628lbv.8 for ; Wed, 15 Oct 2014 14:48:11 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:sender:in-reply-to:references:from :date:message-id:subject:to:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:list-post:list-help:list-archive:list-subscribe :list-unsubscribe:content-type; bh=ZkGZv+mnjuLxXsIzj0eAj5If0e4EcN799CoPLJzUf9E=; b=d6uF6zRwLyaDbsYDtl6HL+w0r9IhMFNexKFnwhL5U3trIWU1F4GxZnQBzugZrjyCNn NM70Rx5GvOa6d8EaXAXkvddO43dvo3y3VgIH9LCCQmI+o1PMsZwVwxixoU2cHnkQKYJA qkNk3AQUyeqC9V4BtOAyaU1ux2APQ1ua1+BQKEOFk+irxBmh7nw7M10OFsYBkhTs4fsL YEHN7gHGxpDLxptT8XH9dyePUFq0+Vm4j0vWoVdSgPB4aFipW88fHULkzfznr3XPxASi hyf4QsW65yiRDrbCOoCblefrsSqxEmIPylZx4CGLs6iR9dK1AGzMQIb1X+gziWZ6wA4A AsRw== X-Gm-Message-State: ALoCoQlJZavMLQfKfPzzFXJvSbDW1sJ7PBymIQfqBgm1FTKw0uGBfCRlLFeuohprEZsD4B0MqOxw X-Received: by 10.180.96.101 with SMTP id dr5mr2574224wib.0.1413409691283; Wed, 15 Oct 2014 14:48:11 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.180.14.106 with SMTP id o10ls184327wic.13.gmail; Wed, 15 Oct 2014 14:48:10 -0700 (PDT) X-Received: by 10.194.90.144 with SMTP id bw16mr5296694wjb.133.1413409690354; Wed, 15 Oct 2014 14:48:10 -0700 (PDT) Original-Received: from mail-wi0-x22a.google.com (mail-wi0-x22a.google.com [2a00:1450:400c:c05::22a]) by mx.google.com with ESMTPS id hj7si26990184wjb.114.2014.10.15.14.48.10 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 15 Oct 2014 14:48:10 -0700 (PDT) Received-SPF: pass (google.com: domain of nliber@gmail.com designates 2a00:1450:400c:c05::22a as permitted sender) client-ip=2a00:1450:400c:c05::22a; Original-Received: by mail-wi0-f170.google.com with SMTP id hi2so253315wib.3 for ; Wed, 15 Oct 2014 14:48:10 -0700 (PDT) X-Received: by 10.180.73.65 with SMTP id j1mr14901211wiv.17.1413409689976; Wed, 15 Oct 2014 14:48:09 -0700 (PDT) Original-Sender: nliber@gmail.com Original-Received: by 10.194.242.198 with HTTP; Wed, 15 Oct 2014 14:47:29 -0700 (PDT) In-Reply-To: <8a74f08b-7453-4d1a-9f20-bc1d3866617c@isocpp.org> X-Original-Sender: nevin@eviloverlord.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of nliber@gmail.com designates 2a00:1450:400c:c05::22a as permitted sender) smtp.mail=nliber@gmail.com; dkim=pass header.i=@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:13939 Archived-At: --f46d043890877e47c305057d168b Content-Type: text/plain; charset=UTF-8 On 15 October 2014 16:17, Myriachan wrote: > While that is a nice feature, it's not the same as needing to do this to > types that weren't created as std::optional. > It is also *extremely* unsafe to do it with any class that can throw an exception during construction or destruction. Why would we want to encourage such a bad habit? I would vote strongly against such a proposal. Even if you SFINAEed it so that it only worked with constructors and destructors marked noexcept, I'd still vote against it, as 99% of users should never use such a function. -- Nevin ":-)" Liber (847) 691-1404 -- --- 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/. --f46d043890877e47c305057d168b Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable

= On 15 October 2014 16:17, Myriachan <myriachan@gmail.com> = wrote:
While that is a nice feature,= it's not the same as needing to do this to types that weren't crea= ted as std::optional<T= >.

It is also extremely= =C2=A0unsafe to do it with any class that can throw an exception during con= struction or destruction.=C2=A0 Why would we want to encourage such a bad h= abit?=C2=A0 I would vote strongly against such a proposal.=C2=A0 Even if yo= u SFINAEed it so that it only worked with constructors and destructors mark= ed noexcept, I'd still vote against it, as 99% of users should never us= e such a function.


--
=C2=A0Nevin &= quot;:-)" Liber=C2=A0 <mailto:nevin@eviloverlord.com>=C2=A0 (847) 691-1404

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