220 29881 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: Sat, 17 Dec 2016 19:14:19 +0100 Lines: 77 Approved: news@gmane.org Message-ID: References: <67a9e9ed-8748-4098-a43b-33598b516464@isocpp.org> <20161217141109.GA22645@manuel-ThinkPad-L440.localdomain> <3df7e8eb-01a0-7804-f476-504b5a25a9fe@gmail.com> <20161217170428.GA10214@manuel-ThinkPad-L440.localdomain> <20161217171633.4919375.58072.21574@gmail.com> <15884364-3238-41c7-bc5a-aa5595a64ade@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary=94eb2c06d7f4cd56140543dea7fa X-Trace: blaine.gmane.org 1481998465 3737 195.159.176.226 (17 Dec 2016 18:14:25 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sat, 17 Dec 2016 18:14:25 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCUMHC4Z6QGBB7MA23BAKGQEBCXXLVI@isocpp.org Sat Dec 17 19:14:21 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-pg0-f70.google.com ([74.125.83.70]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1cIJUv-0008HP-Vb for gclcip-std-proposals@m.gmane.org; Sat, 17 Dec 2016 19:14:18 +0100 Original-Received: by mail-pg0-f70.google.com with SMTP id b1sf85989329pgc.5 for ; Sat, 17 Dec 2016 10:14:22 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=mime-version:in-reply-to:references:from:date:message-id:subject: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=r8RopF+x5+B+nP2X6vjN784+WAONjYKtqfUwvA8G/GE=; b=RNSTW881rKwuSSsAqtr7ARP3oiZxAF/oaP245cOi8LikEU1L5ZhF0gDLwz36mDrJIl a/MSw5GZYb8jr2qb6VVxuFf0Qe2YHUashJUUtkvKOIunSlKb0H0jxBYevkrHaErY5CYz OoYmv4XNrthY9Qz6qQ/oBQelqabpZvcVArJeLE7Zs18XK3DUmOEs9/+vMJYGCuzkfrOe eZInAYdv/DBei1zbo25tKOZgGmCOA9q5h9FpUjv8iaFDUGtPh3LoNMV5FAkm5m9oLzJl sCMzaWi39JLxNZr6JgH8qvUn/9rL1wlmnCIz4F08SK19STAHGZI52N9zSCP2Tklbzb9j wBgA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject: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=r8RopF+x5+B+nP2X6vjN784+WAONjYKtqfUwvA8G/GE=; b=e16VwUcdKZooNYGMi06WyIKogkfvvKXIVkp4kQ1zYVJFfvHLkhUxJbMno6xR3uEpwW aKdYP7fWmu08HVysbkbnCBRn/KsrOEM0HUgZEGOFx2vmNSAWvaX2LNW7Mfm5KCKxbfx5 otznv99QHuqDd85PIQfcmDUtL1oV+d6Zei9BE8rPbdquwC9oXKtq/v4Ax6JOh/Igc5Lu RWBmlPp3W23QheiFT+q5nSWnAHRV7RUWI20fbTt3dQRYPGpMertZjzYp+MZN4rwBio7b ZX5v4S0xdpqyKMf/thBSHPaEFSaCwCuc69wdXenGjq2LTn9JcQtI3VRTx6OuLOOE4Eis Y2ZA== X-Gm-Message-State: AKaTC01W3xmDjypDCnImbrwPd/+H/56Ap4a7qS6sgouVNQm3sBvzjGT2EChrnpi6lPnHSA== X-Received: by 10.99.113.75 with SMTP id b11mr4646909pgn.162.1481998462094; Sat, 17 Dec 2016 10:14:22 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.157.29.137 with SMTP id y9ls10391731otd.39.gmail; Sat, 17 Dec 2016 10:14:21 -0800 (PST) X-Received: by 10.55.184.3 with SMTP id i3mr8920963qkf.7.1481998461159; Sat, 17 Dec 2016 10:14:21 -0800 (PST) Original-Received: from mail-qk0-x233.google.com (mail-qk0-x233.google.com. [2607:f8b0:400d:c09::233]) by mx.google.com with ESMTPS id v6si334569qkl.115.2016.12.17.10.14.21 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 17 Dec 2016 10:14:21 -0800 (PST) Received-SPF: pass (google.com: domain of jonathanmueller.dev@gmail.com designates 2607:f8b0:400d:c09::233 as permitted sender) client-ip=2607:f8b0:400d:c09::233; Original-Received: by mail-qk0-x233.google.com with SMTP id q130so122191022qke.1 for ; Sat, 17 Dec 2016 10:14:21 -0800 (PST) X-Received: by 10.55.157.198 with SMTP id g189mr4691975qke.13.1481998460603; Sat, 17 Dec 2016 10:14:20 -0800 (PST) Original-Received: by 10.55.74.202 with HTTP; Sat, 17 Dec 2016 10:14:19 -0800 (PST) Original-Received: by 10.55.74.202 with HTTP; Sat, 17 Dec 2016 10:14:19 -0800 (PST) In-Reply-To: <15884364-3238-41c7-bc5a-aa5595a64ade@isocpp.org> 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 2607:f8b0:400d:c09::233 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:29881 Archived-At: --94eb2c06d7f4cd56140543dea7fa Content-Type: text/plain; charset=UTF-8 On Dec 17, 2016 7:04 PM, "Nicol Bolas" wrote: > > I don't think "might be harmful" is a good enough reason to not have the type. I think it's a very compelling reason. I rather have types that can be used without thinking, because misuse is a compiler error. > After all, such copying behavior won't break most standard library types. `vector` will work as expected, as will `any`, `optional`, `variant`, and so forth. All of these type work without copy constructing. The only reason you'd need copy constructing there is if you'd need to insert a copy or copy the container. The first one is very easy, just call clone, the second requires a for loop. > I think it's important to understand that `clone_ptr` is a solution to a very specific problem, one that isn't exactly common. You shouldn't see a huge number of these pointers lying around. Yeah, and that's why I can't really see a compelling use case for them. -- 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/CAEddoJa4V_UFj7xcNwR_YNqCfbNtEMbXZgsYDyXCx%3DM51E2xdQ%40mail.gmail.com. --94eb2c06d7f4cd56140543dea7fa Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable

On Dec 17, 2016 7:04 PM, "Nicol Bolas" <jmckesson@gmail.com> wrote:
>
> I don't think "might be harmful" is a good enough reason= to not have the type.

I think it's a very compelling reason. I rather have typ= es that can be used without thinking, because misuse is a compiler error.

> After all, such copying behavior won't break most s= tandard library types. `vector<clone_ptr>` will work as expected, as = will `any`, `optional<clone_ptr>`, `variant<clone_ptr>`, and so= forth.

All of these type work without copy constructing. The only r= eason you'd need copy constructing there is if you'd need to insert= a copy or copy the container. The first one is very easy, just call clone,= the second requires a for loop.

> I think it's important to understand that `clone_pt= r` is a solution to a very specific problem, one that isn't exactly com= mon. You shouldn't see a huge number of these pointers lying around.

Yeah, and that's why I can't really see a compelling= use case for them.

--
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