220 29868 <20161217141109.GA22645@manuel-ThinkPad-L440.localdomain> article Path: news.gmane.org!.POSTED!not-for-mail From: Manuel Bergler Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: New smart pointer: CopyConstructible and CopyAssignable flavor of unique_ptr Date: Sat, 17 Dec 2016 15:11:09 +0100 Lines: 103 Approved: news@gmane.org Message-ID: <20161217141109.GA22645@manuel-ThinkPad-L440.localdomain> References: <13702f32-32c2-447f-9996-3624fd678675@isocpp.org> <67a9e9ed-8748-4098-a43b-33598b516464@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="nFreZHaLTZJo0R7j" X-Trace: blaine.gmane.org 1481983924 24186 195.159.176.226 (17 Dec 2016 14:12:04 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sat, 17 Dec 2016 14:12:04 +0000 (UTC) User-Agent: Mutt/1.5.24 (2015-08-30) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDOZBAUFX4MRBLEP2XBAKGQE5SODU3I@isocpp.org Sat Dec 17 15:11:54 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-lf0-f69.google.com ([209.85.215.69]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1cIFiL-0004NV-2m for gclcip-std-proposals@m.gmane.org; Sat, 17 Dec 2016 15:11:53 +0100 Original-Received: by mail-lf0-f69.google.com with SMTP id c13sf15476795lfg.4 for ; Sat, 17 Dec 2016 06:11:57 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent: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=ZgV5sLVH5OOAGuBTdJZfaIqXwvFLw3B4Dtwb7XNPHag=; b=icYtDxPShxlJGNKtPGKT8aUcx9UuRkl4F7J4Ie0HngI4HU1vC38BXvOCYq2xWugoZ3 X9nTe2edLKM67995FyvEnGQs0uhuTCbP50przZmEoIQ78zGflk6pahhn7JcKP4zP5/1e mekYyhvLBEP3vyxC62ngqSPZy0pKJL1dntcNy3X2KWH9nlQxQ+7S8+fM1tPWjXlWutQw MhasWZJJsANEXzre76kHMJdBt+9+hLA/u7icJ7cGa9tTP9uDb1eYLlKdrTAgVn28Jrzi bBIyDAMijE9JJFLjZUwXXkVt47bAIqSyPHSJJxXIGAK9ZWFyaXFb1uSVcOiv5P380ly1 PP X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent :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=ZgV5sLVH5OOAGuBTdJZfaIqXwvFLw3B4Dtwb7XNPHag=; b=Q7VPIEaZtso1Wi0s4+dumdFA3B9GuhAocKQeY+gnJnpFUnm5DbnykH7idcjVD/7wc6 5wzXulA/glCpiguXt/o5fQJ3KqouZWNhDZZC5y+bVsIQSExAT/9Wot6mtn0MBhr5rF7q 6B0rDvyH7SUMzBJuOzU/b+rf+sSE6/jhhghOHzmXUp8NV0cifuJXKl6R8GuRTfP7zOIv pX2zdxyviwcbRfw2laRtCCPKWew1sCVfgQLAJ/+u3Fq/pFO/n0fhmwnJNWJLNEIHgJPK ++tyOraRX7kaz5KcOVI6H3WxGjhwLBF9QQfP9AtGHiiYaAE96UNICDbo6GP64Po2xW33 X-Gm-Message-State: AKaTC00dpsm05bVO04KyxOt1pgw34Gls7NOusz1vPfDH6kgitJz38FwBm7rz9XpNKnr2kw== X-Received: by 10.25.74.14 with SMTP id x14mr641149lfa.0.1481983917556; Sat, 17 Dec 2016 06:11:57 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.28.154.138 with SMTP id c132ls672878wme.6.gmail; Sat, 17 Dec 2016 06:11:56 -0800 (PST) X-Received: by 10.28.234.85 with SMTP id i82mr6900827wmh.6.1481983916444; Sat, 17 Dec 2016 06:11:56 -0800 (PST) Original-Received: from mail-wj0-x244.google.com (mail-wj0-x244.google.com. [2a00:1450:400c:c01::244]) by mx.google.com with ESMTPS id a5si11885188wji.77.2016.12.17.06.11.56 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 17 Dec 2016 06:11:56 -0800 (PST) Received-SPF: pass (google.com: domain of berglerma@gmail.com designates 2a00:1450:400c:c01::244 as permitted sender) client-ip=2a00:1450:400c:c01::244; Original-Received: by mail-wj0-x244.google.com with SMTP id xy5so17893451wjc.1 for ; Sat, 17 Dec 2016 06:11:56 -0800 (PST) X-Received: by 10.194.52.42 with SMTP id q10mr6714433wjo.50.1481983915890; Sat, 17 Dec 2016 06:11:55 -0800 (PST) Original-Received: from localhost (x5d856f73.dyn.telefonica.de. [93.133.111.115]) by smtp.gmail.com with ESMTPSA id l74sm8221733wmg.2.2016.12.17.06.11.55 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Sat, 17 Dec 2016 06:11:55 -0800 (PST) Content-Disposition: inline In-Reply-To: X-Original-Sender: berglerma@gmail.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com; spf=pass (google.com: domain of berglerma@gmail.com designates 2a00:1450:400c:c01::244 as permitted sender) smtp.mailfrom=berglerma@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:29868 Archived-At: --nFreZHaLTZJo0R7j Content-Type: text/plain; charset=UTF-8; format=flowed Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Sean Parent gave a talk[1] at Code::Dive this year where he talks about the problems of such a clone_ptr type. (He actually starts with a clone_ptr that was proposed to the Standards Com= mittee but is different to the one proposed here, but then discussing alternatives that might seem reasonable) Best Manuel [1] https://youtu.be/cK_kftBNgBc?t=3D40m45s On Sat, Dec 17, 2016 at 02:52:08PM +0100, Jonathan M=C3=BCller wrote: >On 16.12.2016 17:06, Nicol Bolas wrote: >> >> >> I really think this needs to be emphasized. Cheap-move+deep-copy are >> hardly an uncommon set of semantics in C++. Every standard library >> container uses these semantics. >> > > >> >>Oh, and one more C++ standard library type that has these semantics: >>`any`. It requires that the types provided are copyable, and on copying >>an `any`, it will perform a copy (of the exact type provided, of >>course). However, the move may be merely a pointer-shift (to support >>small object optimization, `any`s that store objects with noexcept moves >>may use the object's move constructor instead of the `any` pointer-shift)= .. >> > >Exactly, every standard library *container* uses these semantics. >`std::any` is a container of a single type, so it also uses these >semantics. And this behavior makes sense, for a container. > >Now `std::optional` and the proposed `std::indirect` are not containers, >they behave like a single value, hence their copy/move forward to `T`s >copy/move. This behavior also makes sense. > >Now the copy_ptr here with mixed copy/move would also be a container >- a container of a single type or derived class or something like that. >I don't really see a use for such a container, but alright. > >But the proposed copy_ptr is not really a smart pointer, >none of the other smart pointers do such things, >they simply manage the lifetime of an object. > >This is all my opinion and you're free to ignore me, >but I think this distinction is important. > >Jonathan > > >-- >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/isocp= p.org/d/msgid/std-proposals/e30ffb82-0d5f-fafd-39b4-28e60d07c948%40gmail.co= m. --=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/20161217141109.GA22645%40manuel-ThinkPad-L440.lo= caldomain. --nFreZHaLTZJo0R7j Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEi3F6I6jTgMCHgGvofAJ3kFaTK3oFAlhVR3AACgkQfAJ3kFaT K3pCtBAArO9aHVXdjv/wcdKLfkMObaBNtXGiSMjOgqcC7hnZCfXSyYPlL2HK/H93 I44OmBdiAipexzvK+MWNaFqdEh3hATFYG5A1LeWmXTeLP8kH8sunR7Kjzn0iNS5X KCdAThfdrqr2vUv/6R7QL/2XC1hUuq+zYVLnIrwhnat1RwDzi6/GtYMwvLsEdAkT RU36+fpoxUFB1u32SZRpK70p0hpO99XGyq9a+vnO2EBBRFNlp3qnn6TfIkU7sKSu cge1WbmQ9M59B85CkCuZNHfdz70aPv98kgs9uNgF+jUrlSwv3ieS+cLS9cEJLCJk yrUTF36exUgB24y6uw7rRCTd/oM4kBdaGUtdZoXu7VKvko8+gNw3ROKs7Vt+tD/z FvZbqbBh8cxJueqiGnHM+6OC7atcgh3WcFJJilq+vzaY3gYpifOVPJa8wsgWmjh9 5hX3WzIfGGgUCMD+eqn2e++Mwke6Nbufq+zCi4yCZK30cV3lrMtUzYOkB98XkWdZ UWVHP77ZrHsF7o1AfuQWJafhGuSileVmWgGFB1qIGNCtQxnwSphbY0b9BaQV6aO2 IZG33D+PRYu81WUvfNrcIIiUNOpU3wDEBMuWBmLdbZVTOXvU8GP8Bjm7p/Jbr2vX VrVtonRy2R0yUfbIvCBq/b6fZ37Vja0iWziID+NEo1KCr+M72Hs= =Sf/a -----END PGP SIGNATURE----- --nFreZHaLTZJo0R7j-- .