220 26931 article Path: news.gmane.org!not-for-mail From: Ville Voutilainen Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Proposal - non allocating std::function Date: Thu, 14 Jul 2016 02:26:17 +0300 Lines: 53 Approved: news@gmane.org Message-ID: References: <4948193.1toAHviMXG@tjmaciei-mobl1> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Trace: ger.gmane.org 1468452390 5203 80.91.229.3 (13 Jul 2016 23:26:30 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 13 Jul 2016 23:26:30 +0000 (UTC) To: "ISO C++ Standard - Future Proposals" Original-X-From: std-proposals+bncBC5JHI7A7ALRBHU4TO6AKGQEOKYMVAQ@isocpp.org Thu Jul 14 01:26:24 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-wm0-f69.google.com ([74.125.82.69]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1bNTXr-0002p9-Ov for gclcip-std-proposals@m.gmane.org; Thu, 14 Jul 2016 01:26:23 +0200 Original-Received: by mail-wm0-f69.google.com with SMTP id r190sf44536915wmr.0 for ; Wed, 13 Jul 2016 16:26:23 -0700 (PDT) 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 :content-transfer-encoding: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=nwj+LSO0iAloWxra0h7DacZeWybefUDV9STECnfCG6M=; b=xfwQonqBApSvZmEO3AST9ORRpBXlyywtswPuB/Jm3DG7JrHFDzaD3hwSU5iGjl/z34 Yy+oxGuLEVt4aw5EZZ5TJnQYUA0IXQNvILwbX2vyxQcSARTmgB7qI0vpFJr62By2yHq6 8wrOsKKeWBkDBLB9Ne0nEDnDUtR/fku5o6zsrKdL09d/y3sorwlwZStDRAeb+CDFdhCf 7rWaScUhPlFh9jO3GJu8KWktMwSiPQgfXMMJTuKYkTRJiAzu406EQ0Pl4z+jRQCD4oDN yAUjaOaaAF1agr5Tb8wfM+KJy+KLGFtBe+Cgm7w/pqYYQQf8t4R+TkvUnjw+Y35OCeCy WP/g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:content-transfer-encoding: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=nwj+LSO0iAloWxra0h7DacZeWybefUDV9STECnfCG6M=; b=Zs8sktQm+9zzZihVQ8l4eFogUKGuG+cUeTViUPO6s3xIl9EC78F+i5kXE2fwOFGdOd 5eUHTSctkWQJ8gQ5GmYaxZlPowTP0WFL4OUTSRHaPbYLu8+Q3S0XKOtZ+SyxjkNrAlmJ Mr5RbEDFEHp0wtdzd22MsHU/dvXb4HICoGk/pxovCUx0ylwbtSOi1lciTGL++OnKY3sv 6fras6s3cLZqbYA4JwzCXyqofktt5T2SaVBpq2+SuHpRjuKf3q0NudyNOd/tB8c9RWZM dJmv6cGTyMM9kkc+bOfFS5ApwZaoPZ8XnwEwn1zABtJ/g6wYWuBExxAm95NFNibXNm2R FBt X-Gm-Message-State: ALyK8tLbPYoe4VsGAmIrg550EPjoLhZ1mkMwq+5f3OtoZrxFZ2IWAsCyqkmm8eMGliaMFw== X-Received: by 10.194.23.166 with SMTP id n6mr545392wjf.5.1468452383030; Wed, 13 Jul 2016 16:26:23 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.28.157.65 with SMTP id g62ls64025wme.17.gmail; Wed, 13 Jul 2016 16:26:22 -0700 (PDT) X-Received: by 10.28.129.208 with SMTP id c199mr27859931wmd.79.1468452382294; Wed, 13 Jul 2016 16:26:22 -0700 (PDT) Original-Received: from mail-wm0-x231.google.com (mail-wm0-x231.google.com. [2a00:1450:400c:c09::231]) by mx.google.com with ESMTPS id k3si3853628wmf.64.2016.07.13.16.26.22 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 13 Jul 2016 16:26:22 -0700 (PDT) Received-SPF: pass (google.com: domain of ville.voutilainen@gmail.com designates 2a00:1450:400c:c09::231 as permitted sender) client-ip=2a00:1450:400c:c09::231; Original-Received: by mail-wm0-x231.google.com with SMTP id f126so47305220wma.1 for ; Wed, 13 Jul 2016 16:26:22 -0700 (PDT) X-Received: by 10.28.11.79 with SMTP id 76mr12995086wml.91.1468452381907; Wed, 13 Jul 2016 16:26:21 -0700 (PDT) Original-Received: by 10.28.203.131 with HTTP; Wed, 13 Jul 2016 16:26:17 -0700 (PDT) In-Reply-To: <4948193.1toAHviMXG@tjmaciei-mobl1> X-Original-Sender: ville.voutilainen@gmail.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com; spf=pass (google.com: domain of ville.voutilainen@gmail.com designates 2a00:1450:400c:c09::231 as permitted sender) smtp.mailfrom=ville.voutilainen@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-Spam-Checked-In-Group: std-proposals@isocpp.org 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:26931 Archived-At: On 14 July 2016 at 02:22, Thiago Macieira wrote: > Em quarta-feira, 13 de julho de 2016, =C3=A0s 15:47:44 PDT, Carl Cook esc= reveu: >> Hi all, >> >> This is a cross posting from the SG14 reflector, regarding a draft propo= sal >> some of us are working on. >> >> Very briefly, some of us are interested in having a standardized functio= n >> which does not incur an upfront memory allocation to store the callable >> target, instead opting for a compile time specified buffer (stack >> allocated). This has been quite useful in several low latency domains su= ch >> as gaming and electronic trading. In other words, a drop-in replacement = for >> std::function, where all data is on the stack. >> >> The original post is >> here: >> https://groups.google.com/a/isocpp.org/d/topic/sg14/1Sw_qEdIYes/discussi= on >> >> The resultant draft proposal is >> here: >> https://github.com/WG21-SG14/SG14/blob/master/Docs/Proposals/NonAllocati= ngS >> tandardFunction.pdf > > Hi Carl > > Can you explain somewhere why std::function is unable to do that? > > In other words, why must std::function allocate memory? Because it does type erasure and can hold a functor of any size, and can be assigned to from another functor of any size. Presumably this new type would fail to initialize if a functor larger than the internal buffer is used for initialization or assignment. --=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/CAFk2RUaOii3qgGA7jDZJV6oE-3eoDAQKhmrO8DpUbB3ZVDF= 6Qg%40mail.gmail.com. .