220 21747 <561DE488.3040103@gmail.com> article Path: news.gmane.org!not-for-mail From: Evgeny Panasyuk Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: is await an extension of the do-notation? (was Re: Re: Resumable expressions p0114r0 vs async/await P0057R0) Date: Wed, 14 Oct 2015 08:13:44 +0300 Lines: 42 Approved: news@gmane.org Message-ID: <561DE488.3040103@gmail.com> References: <639f0012-8cb4-4db3-82a6-8d042a3497f9@isocpp.org> <401aa118-ed0b-4c7b-92cf-3fbd706eff9d@isocpp.org> <1d15dbc4-e0c1-4df1-86db-014e11f14d26@isocpp.org> <56114953.4030701@wanadoo.fr> <561B403D.4030403@gmail.com> <561C07D1.3080304@gmail.com> <561C213F.1060009@gmail.com> <561C3875.2050701@gmail.com> <86924069-44d0-447f-bf8a-a42e46579832@isocpp.org> <561D79A7.8080007@gmail.com> <894616d6-9609-4038-b2bc-d2c62df21e0f@isocpp.org> <99bdb3ae-9214-4440-8572-4c47a61eda46@isocpp.org> <58628096-14ae-42b2-89d3-c0bd2183bbc0@isocpp.org> <561DC957.8080603@gmail.com> <510ce172-976a-4e3a-ae68-31fdb40af4d7@isocpp.org> <9dd3f28c-4ffb-4e08-9955-242c46e14527@isocpp.org> <31d5f64f-8db9-4ba3-aca7-872114b9776d@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed X-Trace: ger.gmane.org 1444799643 14911 80.91.229.3 (14 Oct 2015 05:14:03 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 14 Oct 2015 05:14:03 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBC54TLGKR4LBBDWJ66YAKGQEFWWGB5I@isocpp.org Wed Oct 14 07:13:53 2015 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-lb0-f197.google.com ([209.85.217.197]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1ZmENs-0004DR-HV for gclcip-std-proposals@m.gmane.org; Wed, 14 Oct 2015 07:13:52 +0200 Original-Received: by lbwr8 with SMTP id r8sf19654838lbw.0 for ; Tue, 13 Oct 2015 22:13:51 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:subject:to:references:message-id:date :user-agent:mime-version:in-reply-to:content-type: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=SOxbE/Y1Cwy8ABmhhWzFZZq6r36/j/kvuDXpR9/KSyk=; b=FCu1CiQ1rXpVeXNfYE7wQN5Iv++yi0wiXa7zwhpugtyPb+t5CkJc+bpXcFVb164d3G /n+OnYeCFLkpIeSSAJRc4hKG18Jb1C8upozbOKpvAQIw9dv48N0jcKUIfXFTeauadeka itChvSEe9Cb8FVd5QQhtf4iycoMU7Nt8KC/69hAn4/TcvnPtqumFYQ3/FmrgHwR2/ks5 bNqLsmyvRGgWjQZ3cixGhe+KHtTUTcnmX1a/cBAQ3Of2ETyA+MeLeeIeBopshVRzRh5V FYku/NarRlohg4vI03YhM5dDafcoi4JWOI/u//sF8vOuloNF2SgjTHTWb73Jz1dhXPnq xDDg= X-Gm-Message-State: ALoCoQkCfxbG1+oEdE+RIOg4VuQ6hbw7lOF4UVK85N9fJW/LFdVMBpJ4ny+NEvvRWdV6ha/lsFk9 X-Received: by 10.112.181.10 with SMTP id ds10mr246087lbc.3.1444799631762; Tue, 13 Oct 2015 22:13:51 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.25.218.208 with SMTP id r199ls740736lfg.2.gmail; Tue, 13 Oct 2015 22:13:50 -0700 (PDT) X-Received: by 10.25.89.141 with SMTP id n135mr316286lfb.87.1444799630330; Tue, 13 Oct 2015 22:13:50 -0700 (PDT) Original-Received: from mail-lb0-x22e.google.com (mail-lb0-x22e.google.com. [2a00:1450:4010:c04::22e]) by mx.google.com with ESMTPS id z128si4426143lfd.36.2015.10.13.22.13.50 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 13 Oct 2015 22:13:50 -0700 (PDT) Received-SPF: pass (google.com: domain of evgeny.panasyuk@gmail.com designates 2a00:1450:4010:c04::22e as permitted sender) client-ip=2a00:1450:4010:c04::22e; Original-Received: by lbwr8 with SMTP id r8so37951630lbw.2 for ; Tue, 13 Oct 2015 22:13:50 -0700 (PDT) X-Received: by 10.112.200.229 with SMTP id jv5mr487380lbc.123.1444799630019; Tue, 13 Oct 2015 22:13:50 -0700 (PDT) Original-Received: from [192.168.0.186] (81.13.117.87.donpac.ru. [87.117.13.81]) by smtp.googlemail.com with ESMTPSA id e142sm1043481lfe.27.2015.10.13.22.13.48 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 13 Oct 2015 22:13:49 -0700 (PDT) User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 In-Reply-To: <31d5f64f-8db9-4ba3-aca7-872114b9776d@isocpp.org> X-Original-Sender: Evgeny.Panasyuk@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of evgeny.panasyuk@gmail.com designates 2a00:1450:4010:c04::22e as permitted sender) smtp.mailfrom=evgeny.panasyuk@gmail.com; dkim=pass header.i=@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:21747 Archived-At: 14.10.2015 7:51, Nicol Bolas: > If you need only async I/O - yes, I could imagine that extra > allocation is tolerable in such context. But P0057 describes not > only async I/O - but also for instance generators. And for > generators (like transform iterators) an extra allocation is huge price. > > > A price you will never pay because it will be elided. > > Please stop repeating statements that have been disproven; it's not > helping your case. You have yet to post an example of a generator that > would not be elided. I already described it several times, just put generator into some structure/array or return somewhere. In similar situation: http://coliru.stacked-crooked.com/a/0c09744abd5e57ae - allocation of P0057 generator will not be elided, there will be N allocations, i.e. for each coroutine. You can read what Gor said previously in this topic: "If coroutine lifetime is fully enclosed in the lifetime of the calling function, then we can 1) elide allocation and use a temporary on the stack of the caller 2) replace indirect calls with direct calls and inline as appropriate:" There is "if" condition. Even if we assume that optimizers always do elision when condition is true, there is still no elision for cases with false condition. -- --- 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. Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposals/. .