220 26934 <9925907.dlQ8qs8rgK@tjmaciei-mobl1> article Path: news.gmane.org!not-for-mail From: Thiago Macieira Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Proposal - non allocating std::function Date: Wed, 13 Jul 2016 17:20:34 -0700 Lines: 38 Approved: news@gmane.org Message-ID: <9925907.dlQ8qs8rgK@tjmaciei-mobl1> 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 1468455649 21325 80.91.229.3 (14 Jul 2016 00:20:49 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 14 Jul 2016 00:20:49 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCB4TK757YBRBVFVTO6AKGQEX3E4JLI@isocpp.org Thu Jul 14 02:20:41 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-lf0-f69.google.com ([209.85.215.69]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1bNUOL-0001US-Ti for gclcip-std-proposals@m.gmane.org; Thu, 14 Jul 2016 02:20:37 +0200 Original-Received: by mail-lf0-f69.google.com with SMTP id l89sf42461286lfi.3 for ; Wed, 13 Jul 2016 17:20:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=from:to:subject:date:message-id:user-agent:in-reply-to:references :mime-version: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=A3PZXQ6QNFaN1i0esZanZG1Se337UWN4KjxDWE9m48g=; b=Mla7wrkO61YKE88eQmdzdbbGxGbfJgKWYRH06Q8qNfSAN/2q1rfGfkeUQ3EWnw7+AF wfqXFK8q0/lod2//BnuNUiWnY/JyR5tXfsCtsogHeXxMyoUeIozo9TNduEmDa0rzqFRa n4F+kVwHcM+Yr1dsn54eLB+KfHK986RxCX8COUF3BarnEXmyIIwjzx6J2hrkD4b9RjQE krW3LzNCj6Tsf79MAJWqXBAqJjObDpYdt+J1bK9E3k6nukR2n78Opu8Ht+CUyCG/YhPc QufGU3DPDGqwyJdMSUn6bXl0kmzEPhZcCkFKcfzMQQtEYlcIKlSQTrBVIFitkeHV/Q/D X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:subject:date:message-id:user-agent :in-reply-to:references:mime-version: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=A3PZXQ6QNFaN1i0esZanZG1Se337UWN4KjxDWE9m48g=; b=IXWWXmko9cnXLrO7UjP9BW3pzB7VhtSskH5g76gKRnRjhYNMcFX9lNkux+N/PB8Nku eSzZHlNms+pDBE8qlBh3tudnKv51W0i3cg0HCoe8p3ukl7ee7NikNal6fxXTuQvAlFk6 mC20frY0HY3SYIURV3ysstVmr8R5GPFmINGyRYqNMo/ltG+5l6AuWs7DmaG7+P24lHJv bOBbImJDwnJCKKIwbAhEKXRT4UFAJ6IY2OHmksc3XoNyBWN52hxSCEOqE0O3BodeTNfC p2x1HnL0xDnuITXUhfpUt75Fni+qUQToW6QEJxwUO6Lbp7U1JSng22/quYhPSsCbxtmU X-Gm-Message-State: ALyK8tLzlF8Rdj7V+YzLE/mGne1CpiojnbyeDH+8Tpxrq2IdZNMtjS+avQjMZt7UV7pHYg== X-Received: by 10.28.203.3 with SMTP id b3mr1934261wmg.1.1468455637361; Wed, 13 Jul 2016 17:20:37 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.28.27.209 with SMTP id b200ls79040wmb.23.gmail; Wed, 13 Jul 2016 17:20:36 -0700 (PDT) X-Received: by 10.28.27.211 with SMTP id b202mr1654728wmb.12.1468455636328; Wed, 13 Jul 2016 17:20:36 -0700 (PDT) Original-Received: from gondolin.macieira.info (gondolin.macieira.info. [78.47.120.188]) by mx.google.com with ESMTP id a62si30393485wmc.78.2016.07.13.17.20.36 for ; Wed, 13 Jul 2016 17:20:36 -0700 (PDT) Received-SPF: pass (google.com: domain of thiago@macieira.org designates 78.47.120.188 as permitted sender) client-ip=78.47.120.188; Original-Received: from tjmaciei-mobl1.localnet (unknown [134.134.139.77]) by gondolin.macieira.info (Postfix) with ESMTPSA id EC18C11A776 for ; Wed, 13 Jul 2016 17:20:35 -0700 (PDT) User-Agent: KMail/5.2.2 (Linux/4.6.3-1-default; KDE/5.23.0; x86_64; ; ) In-Reply-To: X-Original-Sender: thiago@macieira.org X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of thiago@macieira.org designates 78.47.120.188 as permitted sender) smtp.mailfrom=thiago@macieira.org 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:26934 Archived-At: Em quinta-feira, 14 de julho de 2016, =C3=A0s 02:26:17 PDT, Ville Voutilain= en=20 escreveu: > > Hi Carl > >=20 > > Can you explain somewhere why std::function is unable to do that? > >=20 > > In other words, why must std::function allocate memory? >=20 > 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. Ah, I see: functors (incl. lambdas). I was thinking of function pointers an= d=20 PMFs. Functors can have an arbitrary size, so no std::function implementati= on=20 can be wide enough to hold all possibilities. But as a matter of QoI, std::function should not allocate for regular funct= ion=20 pointers and PMFs, plus stateless functors & lambdas. --=20 Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org Software Architect - Intel Open Source Technology Center --=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/9925907.dlQ8qs8rgK%40tjmaciei-mobl1. .