220 25457 <4187538d-68fa-4582-ba26-f406479abe67@isocpp.org> article Path: news.gmane.org!not-for-mail From: Sean Middleditch Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Relocation as a solution for the valueless variant problem? Date: Tue, 5 Apr 2016 22:19:50 -0700 (PDT) Lines: 62 Approved: news@gmane.org Message-ID: <4187538d-68fa-4582-ba26-f406479abe67@isocpp.org> References: Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_1885_1446217995.1459919990989" X-Trace: ger.gmane.org 1459919996 16891 80.91.229.3 (6 Apr 2016 05:19:56 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 6 Apr 2016 05:19:56 +0000 (UTC) Cc: isocppgroup@denisbider.com To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBCDODCNR2QPRB55YSK4AKGQEWYAP4RY@isocpp.org Wed Apr 06 07:19:55 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-pf0-f197.google.com ([209.85.192.197]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1anfsg-0004Sk-DU for gclcip-std-proposals@m.gmane.org; Wed, 06 Apr 2016 07:19:54 +0200 Original-Received: by mail-pf0-f197.google.com with SMTP id u190sf49499902pfb.0 for ; Tue, 05 Apr 2016 22:19:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc: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=XBaoJBIr6qenczr1icRCXXs8/uiQ7Mzv1puZYM5rSnE=; b=mITYLR2W8FND6mV0AEJBkg+WqbuJ4RYVB+RstX8PzjhiOCsPvZgzNqrKDiu5YnpP2C /9P9QDZTudhtQ2o8vtqKvJXphlPLwTPzI4lLyWtLQOBxboUI/kWtdrwTdPIpUfb2BWio x1UZmffLzJgCE3+iK53A92owsZ6YYqESxOzNGf/fO1ecmkbEgBXPNlaj3nt+1r6/8XGU ZieLmUuSukN4t22tRM/vDNEmYJZk96oTtH9IwGaJGAEaRk22Z8nBQUS8TyudWeB+QP6C 4DEwM+qdhju9MkwaRkR1ykqsv5gvL9DHXCWkHSm8eHJzxgsfW0j0GxDoB0pjGaT+bzKl mZxw== 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:x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=XBaoJBIr6qenczr1icRCXXs8/uiQ7Mzv1puZYM5rSnE=; b=yhQBF5HrY8IabDVcdUr7pu/75xPwoysNjdXX4XSgg7/m5tkH9mHF8Z06B0wpiNfRrS WeT8D/af75zz7B0iDqlTZAoqeql1WwkU+LyKr5tQ99R87+9pEnH7v5l4211yXC/wu4h7 lm1Ejjo1T5vqf+q6+vr2Ml4xTXTUjjBlrBB47lihMdnBOyKB+i0Rf0LalMiJdM84Bzcj 1FstnUG1c9+5wK/KSnkRUTzR0AGR80rlWrmn7CQDddUXQcWAH4uqh1q/ef5eaNcANOFQ LOc2sWvujxk7elozPSPQp0UGYCdB4piqo8kdi2bJxsFwDh/688FCZSETQFUXlyVKHTPC tDBw== 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:x-spam-checked-in-group:list-post :list-help:list-archive:list-subscribe:list-unsubscribe; bh=XBaoJBIr6qenczr1icRCXXs8/uiQ7Mzv1puZYM5rSnE=; b=VZhtkvKJ0nEfvKQd/QcDXNos4hloh3COqeSm88GBUoOmTkDU7V7JXhswkk97XYFzHY osYLVmXWLRjqB+0i15VnZT/XLOOMGIaIpUTZ/ISINWhc92ifOmAg8rZJSkYTopz5pb62 cG7C7SdCYSDyi5496DLH/5GEp9Z2/sHOVH8QC5tkmY1QQBr7f6onBfo4YF9CalAbLosA xRL1Wqc/LLo3vhy7aMyh8kfJScVncvPr97D/Sl2X9hh1lBswk9lCTmwLHIKrEWVJz9Ul CLBcqwrxESH7iVM7sDJuskD/+grgsJD8nR9Zv6ZSOslYEF0dLVL2CowlZAsyxJ5nrX+N CFEg== X-Gm-Message-State: AD7BkJJArgA9udLehbz8kzmUKWycJZd8UCw27DhrqphyZGskICMXGJ5JYCmac8on4iqA9w== X-Received: by 10.66.153.100 with SMTP id vf4mr22474383pab.11.1459919992981; Tue, 05 Apr 2016 22:19:52 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.107.142.142 with SMTP id q136ls340885iod.72.gmail; Tue, 05 Apr 2016 22:19:51 -0700 (PDT) X-Received: by 10.50.160.40 with SMTP id xh8mr432174igb.7.1459919991705; Tue, 05 Apr 2016 22:19:51 -0700 (PDT) In-Reply-To: X-Original-Sender: Sean.Middleditch@gmail.com Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Spam-Checked-In-Group: std-proposals@isocpp.org 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:25457 Archived-At: ------=_Part_1885_1446217995.1459919990989 Content-Type: multipart/alternative; boundary="----=_Part_1886_53620473.1459919990989" ------=_Part_1886_53620473.1459919990989 Content-Type: text/plain; charset=UTF-8 On Tuesday, April 5, 2016 at 4:58:18 PM UTC-7, isocp...@denisbider.com wrote: > > > This would now be exception-safe: > > - without requiring pilfering; > - and without a potentially, but almost never, valueless variant. > Only for types that actually offered the relocation operation. You can't assume that all user-defined types will support this. Thus variant must continue to have some kind of valueless state to satisfy the other constraints. -- 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/4187538d-68fa-4582-ba26-f406479abe67%40isocpp.org. ------=_Part_1886_53620473.1459919990989 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
On Tuesday, April 5, 2016 at 4:58:18 PM UTC-7, isocp...@de= nisbider.com wrote:

This would now be exception-safe:

<= /div>
- without requiring pilfering;
- and without a=C2=A0pot= entially, but almost never, valueless variant.

Only for types that actually offered the relocation operati= on. You can't assume that all user-defined types will support this. Thu= s variant must continue to have some kind of valueless state to satisfy the= other constraints.

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