220 29831 article Path: news.gmane.org!.POSTED!not-for-mail From: =?UTF-8?Q?Jonathan_M=c3=bcller?= Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: New smart pointer: CopyConstructible and CopyAssignable flavor of unique_ptr Date: Fri, 16 Dec 2016 13:36:33 +0100 Lines: 42 Approved: news@gmane.org Message-ID: References: <13702f32-32c2-447f-9996-3624fd678675@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; format=flowed X-Trace: blaine.gmane.org 1481891798 25266 195.159.176.226 (16 Dec 2016 12:36:38 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Fri, 16 Dec 2016 12:36:38 +0000 (UTC) User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1 To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCUMHC4Z6QGBBU57Z7BAKGQE7UBQBXQ@isocpp.org Fri Dec 16 13:36:33 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-wj0-f200.google.com ([209.85.210.200]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1cHrkW-0005Sy-AH for gclcip-std-proposals@m.gmane.org; Fri, 16 Dec 2016 13:36:32 +0100 Original-Received: by mail-wj0-f200.google.com with SMTP id xr1sf34706646wjb.7 for ; Fri, 16 Dec 2016 04:36:37 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=subject:to:references:from:message-id:date:user-agent:mime-version :in-reply-to: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=zYy1FpKaXiXck+e6LmOL/31gYG2JYQspDgwEpekZxyI=; b=Q7cVsFLPJgLYtqmXbWVC5qxKMdiShRlU48k9z3cmel93cKWs+GvwcnfcNyEiqw1Jfo ZinT3JYZ4DuBUVeYxZF3OQDbftVx+6RPxELn7h/3SQOIxkGWl79lZGJq5/SMREPByj8O I4+GbEeicfPR1tIsRIoBPntIFoV9xeJhqIJY/hW5iPMLqiBEassKz8lcdzr3YSVWkX8t TZn+bqpTgYzd0o4ikl9ZLaYU06eektWKeVmSPVEXNHfzm3MJ2eS5bHu6pxqB7Ljp3Ltz Ar1DU6SItVLaqJMyrsa/1tFNd8eeG52WLw5FzEAtIWYOynDowA1yW4b0UHR4GOb0oTMn 5GYw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:references:from:message-id:date :user-agent:mime-version:in-reply-to: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=zYy1FpKaXiXck+e6LmOL/31gYG2JYQspDgwEpekZxyI=; b=YLsjlBH/Xor5U7XX0IoHRbI1/ILxmr6iLtiRzTjJYFgSSrRWL+wkt5WqWNb2L2fshq c33Qi4eHjgQ2+5QLD031LTlv+rnO5XGsA7C9Q6/QtOXNR1y4PF1Ab8qRzhvgHnVbaGLx GmmQav2DhHaop5QR9CtPRT1geNTreLgxrcprPGLniMFt6LtVYJphCiAEBQVZfxJOi0Cs yRK+bGP6G11XrVzA/rQfsyV6qgXsJSM7oyOb9JGnC2RxTBUPGxBklwhLj3XIHAcERQiu fC4wmyVWaUzbNxxE/nmJaXcumEquVP+oTgik2E0/K7a1P5BYtBxxsUxNIn1d8JoW9CLF ZvSA== X-Gm-Message-State: AIkVDXIkBhkzMJ3RSUcD/Q8AUMo5OQQ83oyjtjsAu08U/WZgq5WyET/Qb1Xdff0ybHUb3g== X-Received: by 10.46.77.66 with SMTP id a63mr228635ljb.22.1481891796888; Fri, 16 Dec 2016 04:36:36 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.28.18.133 with SMTP id 127ls294700wms.10.canary-gmail; Fri, 16 Dec 2016 04:36:35 -0800 (PST) X-Received: by 10.194.93.104 with SMTP id ct8mr3009834wjb.87.1481891795456; Fri, 16 Dec 2016 04:36:35 -0800 (PST) Original-Received: from mail-wj0-x243.google.com (mail-wj0-x243.google.com. [2a00:1450:400c:c01::243]) by mx.google.com with ESMTPS id aj4si6818004wjd.196.2016.12.16.04.36.35 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 16 Dec 2016 04:36:35 -0800 (PST) Received-SPF: pass (google.com: domain of jonathanmueller.dev@gmail.com designates 2a00:1450:400c:c01::243 as permitted sender) client-ip=2a00:1450:400c:c01::243; Original-Received: by mail-wj0-x243.google.com with SMTP id kp2so14391803wjc.0 for ; Fri, 16 Dec 2016 04:36:35 -0800 (PST) X-Received: by 10.195.14.7 with SMTP id fc7mr2790678wjd.198.1481891794992; Fri, 16 Dec 2016 04:36:34 -0800 (PST) Original-Received: from [134.61.95.229] (095-229.eduroam.rwth-aachen.de. [134.61.95.229]) by smtp.gmail.com with ESMTPSA id w18sm3192457wme.9.2016.12.16.04.36.34 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 16 Dec 2016 04:36:34 -0800 (PST) In-Reply-To: X-Original-Sender: jonathanmueller.dev@gmail.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com; spf=pass (google.com: domain of jonathanmueller.dev@gmail.com designates 2a00:1450:400c:c01::243 as permitted sender) smtp.mailfrom=jonathanmueller.dev@gmail.com; dmarc=pass (p=NONE dis=NONE) header.from=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:29831 Archived-At: On 16.12.2016 13:25, Jonathan Wakely wrote: > p0201r1 deals with that problem, which is why it's a better approach. On 16.12.2016 13:28, Ville Voutilainen wrote: > Like the proposed std::indirect? I got the impression that its latest > feedback was to move it > closer to value semantics of a polymorphic type. Yeah, exactly. I like `std::indirect`, it behaves like a `T` and has consistent semantics. > But I do, otherwise I wouldn't have chosen a cloned_ptr. Alright, hard to argue with that and I get your arguments. I just don't think that's particularly "clean". If the type wasn't polymorphic you'd embed it as a member directly, so copying will copy all members and moving will move all members. But if you change it to use a polymorphic type you use a cloning_ptr, so copy will still copy everything but moving will suddenly leave the type with an "empty" member? I wouldn't like using that struct with that change. There might be a possible use case for cloning_ptr, but I don't think its as a member. And if you don't use it is a member, you don't need a copy constructor but can use a free function. > All pointers are a mix between "optional" and something else since > they can be null. And that's > just fine for many cases. I meant on a semantic point of view: mix between value semantics and ownership transfer. -- 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/c8c29792-37a9-2eb1-1a5e-69ccfe247661%40gmail.com. .