220 29876 <20161217170428.GA10214@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 18:04:28 +0100 Lines: 70 Approved: news@gmane.org Message-ID: <20161217170428.GA10214@manuel-ThinkPad-L440.localdomain> References: <67a9e9ed-8748-4098-a43b-33598b516464@isocpp.org> <20161217141109.GA22645@manuel-ThinkPad-L440.localdomain> <3df7e8eb-01a0-7804-f476-504b5a25a9fe@gmail.com> 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="XsQoSWH+UP9D9v3l" X-Trace: blaine.gmane.org 1481994318 1014 195.159.176.226 (17 Dec 2016 17:05:18 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sat, 17 Dec 2016 17:05:18 +0000 (UTC) User-Agent: Mutt/1.5.24 (2015-08-30) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDOZBAUFX4MRBTHA2XBAKGQEK62LU3I@isocpp.org Sat Dec 17 18:05:13 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-lf0-f72.google.com ([209.85.215.72]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1cIIQ4-0007RS-VV for gclcip-std-proposals@m.gmane.org; Sat, 17 Dec 2016 18:05:13 +0100 Original-Received: by mail-lf0-f72.google.com with SMTP id y21sf16503917lfa.0 for ; Sat, 17 Dec 2016 09:05:17 -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=FsL8rF7bbL4RJKN9LoPju8qes6RdqK7bymxXH8zHkLQ=; b=jRPQYYm3rdSnDSU/1iPfOI/TQu6b2VacDCzyuIKA0PdJPUaqh3NVqQoY5Z5jUialHV Dy4pyE5jakBOHKEJepjE0ayqpcRaYvcVk2MHcBGVgwmtgGmgPP/4o+rztapALmIC1fnf jKkx+3iqmTN2cDAevXkJoc5sWXgF53HOmoVW+dlV/3M0WT9AWAhEQVM4zX5P5ag0uPTT 99FVKs0a+OJpfCEofyF1uigT3wCcOjahQsCHXh59/BJSBHB6nS87gIvEP4ENdOr19/Tr 5PgdKUFtcgJxQlIph0hrW0x8363tmvPdLlcG13Vg3arTTMr1yIeKiJwLOyNM5RtJWNeX se 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=FsL8rF7bbL4RJKN9LoPju8qes6RdqK7bymxXH8zHkLQ=; b=E3MNTb/mpe/7xtDGi4SXDJeHKHHpO9guVh5R23HpUudqh5HWffnb2Zzqaavhka8ObC bByadsxpYRqpEhu6HWfDUaHI2jtPTf+AcGwye6NI2zHsYvDpMPCBMKoDatRzUzihOaIC 0CfmUVSMru/Ym9sEv/QI9qX1Vv97VZzkYa6aiJBUdsTkkVoUGUZQtBPHo1KJIST6Dmog CzjgpJ0s7Gmd72hE6CBaA7OFI+oJ/r66ZanEy3NNq3h4hnvXs1v8Y4UFNIznb/46Wd+4 3IrjxtAIRRZ/Uax7GU2R2SBhAE2lpR+4r4+ovieZBa8DO/NHYi2YsRohLlO2aECB6cxt X-Gm-Message-State: AIkVDXL7VkZI3PVv8Kpb9n7vvLjgYt2XzTQY364vj2awdg0wlcMvs6XLn53x0XzomNsijg== X-Received: by 10.46.8.17 with SMTP id 17mr846027lji.26.1481994317389; Sat, 17 Dec 2016 09:05:17 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.28.140.6 with SMTP id o6ls698335wmd.7.canary-gmail; Sat, 17 Dec 2016 09:05:15 -0800 (PST) X-Received: by 10.194.122.101 with SMTP id lr5mr7276635wjb.210.1481994315618; Sat, 17 Dec 2016 09:05:15 -0800 (PST) Original-Received: from mail-wj0-x241.google.com (mail-wj0-x241.google.com. [2a00:1450:400c:c01::241]) by mx.google.com with ESMTPS id nb7si12311758wjb.12.2016.12.17.09.05.15 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 17 Dec 2016 09:05:15 -0800 (PST) Received-SPF: pass (google.com: domain of berglerma@gmail.com designates 2a00:1450:400c:c01::241 as permitted sender) client-ip=2a00:1450:400c:c01::241; Original-Received: by mail-wj0-x241.google.com with SMTP id j10so18315865wjb.3 for ; Sat, 17 Dec 2016 09:05:15 -0800 (PST) X-Received: by 10.194.146.131 with SMTP id tc3mr7584179wjb.129.1481994314985; Sat, 17 Dec 2016 09:05:14 -0800 (PST) Original-Received: from localhost (x5d856f73.dyn.telefonica.de. [93.133.111.115]) by smtp.gmail.com with ESMTPSA id jm6sm12203444wjb.27.2016.12.17.09.05.13 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Sat, 17 Dec 2016 09:05:14 -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::241 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:29876 Archived-At: --XsQoSWH+UP9D9v3l Content-Type: text/plain; charset=UTF-8; format=flowed Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sat, Dec 17, 2016 at 06:10:10PM +0200, Ville Voutilainen wrote: >On 17 December 2016 at 17:35, Jonathan M=C3=BCller > wrote: >> On 17.12.2016 16:29, Ville Voutilainen wrote: >>> >>> Such a type has just one problem: it's close to useless. It doesn't >>> violate Sean's lofty principles, >>> but it doesn't solve the problems it's aimed for either. >> >> >> What are the problems it's aimed for exactly? > > >Convenient cloning, and automatic cloning when passed by value or >returned by value, including when >wrapped under something else as a member. Needing to manually invoke a >clone function more or less >completely defeats that purpose. > I might miss something here, but I can't think of a use-case where the conv= enience of returning it from a function by value having it implicitly clone= the pointee with `return my_clone_ptr;` instead of just writing `return my= _clone_ptr.clone();` is worth sacrificing the clarity of the latter version= , in particular since you might actually have intended to move it but forgo= t to call `std::move` on it before returning. So as far as I can tell the only remaining benefit is that you needn't writ= e a custom copy/move constructor/assignment operator for a struct/class hav= ing one of these as a member? --=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/20161217170428.GA10214%40manuel-ThinkPad-L440.lo= caldomain. --XsQoSWH+UP9D9v3l Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEi3F6I6jTgMCHgGvofAJ3kFaTK3oFAlhVcBoACgkQfAJ3kFaT K3rQuhAAs/KAVJviC5Q1OyII4DTO7ZCWgIgqtU+jyK6g1Y+UJOZubb96UHDSLJ3G piljmowEOaGbztLlFfs1yhuncqYPV8YMXBp2miX+TkNeS09uIU5rb1bWY4jmd51l nsiw9e/oTPqdngD83Z/ZyZXGxX2P8cSPiftqbyvWmbus/ai75e1I8TeFPr36llHF jAgwZcem8P7aoG7zMqEi9Wa3aXyi0wZ29k4bEZvnRuvrZ8tWjF47KJQtZSgqI8AD FLvXwcskWMrxbpd7OA0hdbGG+oZ9MjJmj4teTcRBiRP2lE5feP5RluE9YG3M3EEH c/wPmpil3BtuY0oldtCIw3q7hoGXwKC/M/g+4WJugd+BjPNPmrNB4+0ljbiYdJ0b a8jE/DwC+mVZEWXoNXNLm9MW9TZbO3+DjgoAD4e9lQNWdLDoczAlqgrJK1/K/TV1 uAjofNXkZRO1ztzEL9Rx5QrbZwa8daWi340K/ERH3hTHtzFn+d2cwqDsucdJce6Z 7B4XoLhgLXoB0Xy2BRglxGflZp3k1A5YNzwak1PaEoJUFAo4De3dRtETKdBi1Mpf FQiPODNCk/Ix2bTveehDmd8CUBUMRh3YxWNisVYA7w6fh983k0vm0AnEcn5y278a pLvydgiRGLTgMmCOSYUCCvyEwGIWWiWtKI9ABRybUqqGmG0WKvk= =UjIz -----END PGP SIGNATURE----- --XsQoSWH+UP9D9v3l-- .