220 34958 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 02:24:01 -0700 (PDT) Lines: 114 Approved: news@gmane.org Message-ID: References: <0a8293b4-3246-47a5-9881-bc1ca4b91772@isocpp.org> <16a45cfa-8016-4f9d-8d6c-48d1e73c4874@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_17221_703955355.1508145841893" X-Trace: blaine.gmane.org 1508145845 3157 195.159.176.226 (16 Oct 2017 09:24:05 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Mon, 16 Oct 2017 09:24:05 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBDNMBNHJWIGBBMXVSHHQKGQE6L36C5Q@isocpp.org Mon Oct 16 11:23:59 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-vk0-f70.google.com ([209.85.213.70]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1e41cq-0008CB-Ru for gclcip-std-proposals@m.gmane.org; Mon, 16 Oct 2017 11:23:57 +0200 Original-Received: by mail-vk0-f70.google.com with SMTP id 137sf5754924vkk.11 for ; Mon, 16 Oct 2017 02:24:04 -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=Bcgpc6EMk1cS5ia1AithyWF2zTcLurult1oxAnUuGak=; b=mUT/GKAGnAXFqwQizniAA+mvMvcFRIXb5Sm5hE4kgiMeMw6KdDEPzLg8OxZmWGKwC8 vAO+j16qn6nDeBebpZk/17+iZ3zCXwiW9NSljD5GQPfoU6d7xALPF4NZ0EALG6motrCU iyEfOq9RKGdXQDjvX4B2XyR0vXCPIWQAXAVN7gX/cSJ1TND2J+gVMQ1bZPjBksyJAecc RM6s9NII80C8iRNsu4QpPTI6bkPqEVffkH/cMwfRpi0/BWn8EReIo4fhrkORPcjzRmmP fgcmtuFade9kWjSVwkDk1bMFYnMQ4cwhhNlq5n1aRCzCmq/hQb9FCtnsFKNma5ggsyeo a5Nw== 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=Bcgpc6EMk1cS5ia1AithyWF2zTcLurult1oxAnUuGak=; b=eg7nZb4yOv6zKhRXjRqw7mb8ioAcfoGy6jjjcMNlByICJm0mFBBWPCzt+8SqeHKXdP Pc+EWchxPOQWeYqZ3kjBcwCta2G5yR6m/NMW317xxNbJbYs/o/f4fpZE/XAoIz2b4WYI 9qYPbMVRCp+Y8lslkh2idTfODmaKAF/pNLL2Jtay0dhl0ZN40GcAhSWXF8IPlCFguu1A pEssAmBGTg5xEwI/FUXkZsjFqO5Ux32/kY5I1TbuOEj6YTeWD6uJUGyAlAHPn+wKtIWU /jp78F8e1uVOdDZherW6xzLOjCmIc4mr+if/WpCVeLgaEA+8OOe+YyvnJ7PeEU8mXaBD 3v+Q== X-Gm-Message-State: AMCzsaWUJtinE8CAz9IyS2HbPusxeVMTrjhcRbOzks0jZhYgetlL7/nk 4Jsfi+Eb1Z9fHZoTw2pQ+za51A== X-Google-Smtp-Source: AOwi7QDTgpIaVSz7NnZd27IpL6krV+TOJrGpUdp9EMf/Y1W3vMP1Ih6TlgjdxP/Uhc8MGTCEUIj3+w== X-Received: by 10.31.124.136 with SMTP id x130mr4795629vkc.44.1508145843996; Mon, 16 Oct 2017 02:24:03 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.31.67.200 with SMTP id q191ls2971178vka.7.gmail; Mon, 16 Oct 2017 02:24:02 -0700 (PDT) X-Received: by 10.31.168.133 with SMTP id r127mr359544vke.8.1508145842587; Mon, 16 Oct 2017 02:24:02 -0700 (PDT) In-Reply-To: <16a45cfa-8016-4f9d-8d6c-48d1e73c4874@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:34958 Archived-At: ------=_Part_17221_703955355.1508145841893 Content-Type: multipart/alternative; boundary="----=_Part_17222_149021227.1508145841893" ------=_Part_17222_149021227.1508145841893 Content-Type: text/plain; charset="UTF-8" On Monday, October 16, 2017 at 6:04:26 AM UTC+8, Arthur O'Dwyer wrote: > > What you are describing has already been implemented (and proposed, > AFAIK). It is an excellent idea. I don't know why it didn't get into C++17 > along with all the other pieces of PMR that did. > http://en.cppreference.com/w/cpp/experimental/resource_adaptor > > `std::experimental::pmr::resource_adaptor` seems not what I have suggested. I think "MemoryResource" has lower level semantics (provides more basic service) than "Allocator" does, and therefore "Allocator" could be "MemoryResource"'s user. On the contrary, defining a basic service with an advanced one seems logically unreasonable, so I do not suggest `std::experimental::pmr::resource_adaptor` should be included in the standard. However, PMR will never be all things to all people. You should certainly > read my paper P0773R0 "Towards Meaningful Fancy Pointers" > in the upcoming > pre-Albuquerque mailing; it will clarify your thinking about "what is an > allocator" and especially "what does allocator equality mean"; and it will > make you much more pessimistic about the chances of shoehorning the full > C++11 allocator model (including fancy pointer types) into type-erased > things like polymorphic_allocator, function, and any. > Thank you for the paper! However, I am targeting at neither "Allocator" nor "the full C++11 allocator model". The target in this discussion is the PMR system. 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/bb3ae52c-c3be-4966-a8d5-731b6f68919b%40isocpp.org. ------=_Part_17222_149021227.1508145841893 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
On Monday, October 16, 2017 at 6:04:26 AM UTC+8, Arthur O&= #39;Dwyer wrote:
What you are describing has already been implemented (and proposed,= AFAIK). It is an excellent idea. I don't know why it didn't get in= to C++17 along with all the other pieces of PMR that did.
=

`std::experimental::pmr::resource_ad= aptor` seems not what I have suggested. I think "MemoryResource" = has lower level semantics (provides more basic service) than "Allocato= r" does, and therefore "Allocator" could be "MemoryReso= urce"'s user.=C2=A0On the contrary, defining a basic service with = an advanced one seems logically unreasonable, so I do not suggest `std::exp= erimental::pmr::resource_adaptor` should be included in the standard.
=

However, PMR will never be all things to all people. You = should certainly read my paper P0773R0 "Towards Meaningful Fancy = Pointers" in the upcoming pre-Albuquerque mailing; it will clarify= your thinking about "what is an allocator" and especially "= what does allocator equality mean"; and it will make you much more pes= simistic about the chances of shoehorning the full C++11 allocator model (i= ncluding fancy pointer types) into type-erased things like polymorphic_allo= cator, function, and any.

Thank= you for the paper! However, I am targeting at neither "Allocator"= ; nor "the full C++11 allocator model". The target in this discus= sion is the PMR system.

Mingxin Wang

--
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