220 34962 article Path: news.gmane.org!.POSTED!not-for-mail From: Mingxin Wang Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Idea about "std::pmr::memory_resource" Date: Mon, 16 Oct 2017 05:08:45 -0700 (PDT) Lines: 117 Approved: news@gmane.org Message-ID: References: <0a8293b4-3246-47a5-9881-bc1ca4b91772@isocpp.org> <07ddb1f6-d3af-43df-bf96-8975c1ab4313@isocpp.org> <2e191a96-1952-479b-b78b-22e31f8e03de@isocpp.org> <0e37b5ae-64f6-4a8a-86bd-f44b119ed40a@isocpp.org> <15f8c5ba-3a6a-4441-9620-92e157c66094@isocpp.org> <26fe4cb4-98ca-41cc-ac96-5c51851799d1@isocpp.org> <784ffce8-ace7-449d-a13d-a99d7336117a@isocpp.org> <6d0ad98b-87d5-43dd-ac54-2b7d3e03e31b@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_6073_1887928021.1508155725476" X-Trace: blaine.gmane.org 1508155726 8564 195.159.176.226 (16 Oct 2017 12:08:46 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Mon, 16 Oct 2017 12:08:46 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBDNMBNHJWIGBBTWCSLHQKGQEJZ7GXNI@isocpp.org Mon Oct 16 14:08:40 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-vk0-f69.google.com ([209.85.213.69]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1e44CF-0001Ts-Vs for gclcip-std-proposals@m.gmane.org; Mon, 16 Oct 2017 14:08:40 +0200 Original-Received: by mail-vk0-f69.google.com with SMTP id c76sf6024219vkd.14 for ; Mon, 16 Oct 2017 05:08:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:message-id:in-reply-to:references:subject:mime-version :x-original-sender:reply-to:precedence:mailing-list:list-id :list-post:list-help:list-archive:list-subscribe:list-unsubscribe; bh=+LeZx5BQ/b8egmkOXZ6Qd97nxiP6zf/QSFLgK3w8KGk=; b=hABHnTafUFP+RIKdRHNNQOGPd9i2zCBlcBpJB6f5CWLZxBrqR3xU3IAng/tj7pRb5o Dm/4nXHhjhj8crCtFiS4AavR1z+q/2xN8TQT7puedoeyKe0CoQUmRiqMS06K0zAfqo/E k1AOTGhQjaa9ZYPcE6iVou0fPHmTWBz0KgBviqKCflKQM312nhyKZ0qE947eHEfWExJU B0TrH6jWl+hLLXMJnsj9mIS5G3krq0IS/sVFfMBfr9PsQ0TUe+Fb5uFzH5xUOj99Rkpd InmGDque0JXVK2RIZE826gf+mNjW646pjySxLVYrYE1age1x1WTH8Ar8ez0QzvR1WZWj qy9A== 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: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=+LeZx5BQ/b8egmkOXZ6Qd97nxiP6zf/QSFLgK3w8KGk=; b=bMFxmDkipK6QzvAsqAzU9Bo389UOXRvwAQzMzLnVYseUXCV6IqnPIAnFh5HTRPa1T0 jK+PH/IvIhtxIwW5FkxKNtPYL3wHN7iYdq12EUyUOuvKl3jhzVmSesENIcbnpNl4IYFQ uK3k57Cu7S3EoaDBGUcCjN02tDpxZ24oMIbg5ZhHb1l717IuS7ok8134dh97VPJ1QD/J n4+G4QGqNmONwg6hTQbbVju9UYadKm3Ch9klE3Du3W86xMFmN6X4Ku3BjJK0skPuoPGm YT22hL/QPihLYc2LvWZqmsjJUoyn+r6MbvE/SfGfHvjEWIZDRK/T8WliUo6EVU1zNRUj 1dHw== X-Gm-Message-State: AMCzsaU/d0gvYM4mL6cm5LPdFvbbtQEoeQx17yAeeVtTLxZDWczEZJ/T HQLKppmzvFGG6h32Widwl3OEfw== X-Google-Smtp-Source: AOwi7QAF6TQOjCYtBWCw4CNqegfEtEVN19RAIJ3gGLbdCc9O0cmE73MsrmLEPP7T0jmnLoi4pqy+sA== X-Received: by 10.159.59.10 with SMTP id i10mr5038619uah.61.1508155727370; Mon, 16 Oct 2017 05:08:47 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.31.138.69 with SMTP id m66ls3218950vkd.15.gmail; Mon, 16 Oct 2017 05:08:46 -0700 (PDT) X-Received: by 10.31.137.138 with SMTP id l132mr369762vkd.14.1508155726043; Mon, 16 Oct 2017 05:08:46 -0700 (PDT) In-Reply-To: <6d0ad98b-87d5-43dd-ac54-2b7d3e03e31b@isocpp.org> X-Original-Sender: wmx16835vv@163.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:34962 Archived-At: ------=_Part_6073_1887928021.1508155725476 Content-Type: multipart/alternative; boundary="----=_Part_6074_859882170.1508155725477" ------=_Part_6074_859882170.1508155725477 Content-Type: text/plain; charset="UTF-8" On Monday, October 16, 2017 at 6:55:41 PM UTC+8, Aleksey Loginov wrote: > > Let's look at a more applied example: > > template > struct static_resource : memory_resource { aligned_storage_t m_data; > }; > > template > struct my_any; > > > my_any x1; > my_any> x2; > > x1 = 1; > x2 = x1; > > assert(x2 == 1); > > > How can you do this without RTTI? > And I don't think `x2` should be copy-assignable from `x1`, if - `static_resource<32>` is not copy-constructible from `default_memory_resource`, or - the two memory resources could not be reflexive (being reflexive means, you could allocate some memory from one, and deallocate the memory from another). Mingxin Wang -- 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/bd58ac93-5d20-48e6-93cc-b07a727ce892%40isocpp.org. ------=_Part_6074_859882170.1508155725477 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
On Monday, October 16, 2017 at 6:55:41 PM UTC+8, Aleksey L= oginov wrote:
=
Let's look at a more applied example:

template<<= span style=3D"color:#000">size_t Size>
struct st= atic_resource : memory_resource { aligned_storage_t<Size><= /span> m_data; };

te= mplate<typename MR>
struct=C2=A0my_any;


my_any<default_<= span style=3D"color:rgb(0,0,0)">memory_resource> x1;
my_any<static_resource<32>> x2;

x1 =3D 1;
x2 =3D x1;=

assert(x2 =3D=3D 1);


How can you=C2=A0= do this without RTTI?

And I don= 't think `x2` should be copy-assignable from `x1`, if
    `static_resource<32>` is not copy-constructible from `default_memory= _resource`, or
  • the two memory resources could not be reflexive (bei= ng reflexive means, you could allocate some memory from one, and deallocate= the memory from another).
Mingxin Wang

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