220 26942 article Path: news.gmane.org!not-for-mail From: Nicol Bolas Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Proposal - non allocating std::function Date: Wed, 13 Jul 2016 19:15:40 -0700 (PDT) Lines: 102 Approved: news@gmane.org Message-ID: References: <871t2xqbb5.fsf@gmail.com> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_76_678687218.1468462540724" X-Trace: ger.gmane.org 1468462545 29190 80.91.229.3 (14 Jul 2016 02:15:45 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 14 Jul 2016 02:15:45 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBCEKFTV6ZUMBBTPLTO6AKGQETE4B4EA@isocpp.org Thu Jul 14 04:15:45 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-it0-f70.google.com ([209.85.214.70]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1bNWBj-0006Je-Lq for gclcip-std-proposals@m.gmane.org; Thu, 14 Jul 2016 04:15:43 +0200 Original-Received: by mail-it0-f70.google.com with SMTP id g8sf128511967itb.2 for ; Wed, 13 Jul 2016 19:15:43 -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 :x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=eLZcFfmzv2shG+g7R0yx+x3HHR1tdZMpjqrMsG0C9FE=; b=BZwqU12M89n92e+VRLVK1k40rUOWmqlJlpF5p6pOkg5JdJXKkUT9HRER6rYmTwrsuO kUm5qaH72XUiblFQFpwmgy+/BzJCZV5zIjqRw060PYR/57LUfiLYl6BEtHDv/w5nJP8m B8XqwCu0EdSP9Ys4U2XGBoboqfumdPuweutv2aATSb8hqhjbbinflXf1QrkGXo4q7wEW FTNHb+4uwE1yFbmCwQGDNTIDFs9LP+SEzZLFWCyursV/y5KHa5zyifg5WrYOcUacS/Oy I4ix9INFlPGrmyUiS82xFYpEbZNqaGru4jdqhgib65xCf0me55NGtRKy9GOSIZpUTYop qJSA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=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=eLZcFfmzv2shG+g7R0yx+x3HHR1tdZMpjqrMsG0C9FE=; b=sVIxboI/0XlOqs6homYDldMHpPsYj1RA/ML3NVNUr3Ob5oAUuCeffz9G7QzOU/bQUO zsVhzil/jmodi0Dxgox3Sp1wV9/H5r9mhhbuvtm9r+T2MxpHC/ZJX1ejWG+Km87m8JYa EATQ90KOSvML65RGmZvvELla7mgW3N1YUx9Dam9Tv3rwa+h4rJumpXZv9Hb7XBLZeduV ajJDN5P/3fCJ3Kuw09qS9OFHKExs915NZp1GTJlgjWde9gicX1HS7mE7OIKIWBgNdc/7 uLkOIMG2QJj2hcN2nV+U8N7vfmlRfQhKZjiX6H09vz3HXYd7WTJ73P9tZDADEvz6tbkn dKIA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; 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=eLZcFfmzv2shG+g7R0yx+x3HHR1tdZMpjqrMsG0C9FE=; b=j2qjPCXcjkB8JGTgwBGpj+4EjsjxEbg4TNhwMvtjSXwzXADlAzxY5rs9HoihIxVSDQ sMI+30JNcok4soojaxdhu6V/mfcCx55wWg64qHG/IeenEnUQgYK/NsZRfit6wfby5ZBx R5ql9KcD2kBwuIs3HP8MJZWCj0ONOHTHLubbLGmgAD21r4nnAdKbOzc6j1Q/ramvtm3j qPsTiBZ5dvyCAL21+mQB3W1meqqk2G7br9U5R78FxIT32SEUiV85btcAqhMQjSur+KwI J63QTG2Z4KCOEzW8K1StyWQPb0ckFhbE5IWVqf8JrQ6QyDuoePm0s0UPLJyDvTy3UBKm JI3A== X-Gm-Message-State: ALyK8tKeMNYioR3F14ei5XSJMHLSigeaMpYuNlufmnshMCLG7WDPodWec8JK0Ru1+784CQ== X-Received: by 10.107.34.7 with SMTP id i7mr9277546ioi.17.1468462542784; Wed, 13 Jul 2016 19:15:42 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.107.32.205 with SMTP id g196ls232277iog.51.gmail; Wed, 13 Jul 2016 19:15:41 -0700 (PDT) X-Received: by 10.36.50.75 with SMTP id j72mr835318ita.5.1468462541756; Wed, 13 Jul 2016 19:15:41 -0700 (PDT) In-Reply-To: <871t2xqbb5.fsf@gmail.com> X-Original-Sender: jmckesson@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:26942 Archived-At: ------=_Part_76_678687218.1468462540724 Content-Type: multipart/alternative; boundary="----=_Part_77_800067329.1468462540724" ------=_Part_77_800067329.1468462540724 Content-Type: text/plain; charset=UTF-8 On Wednesday, July 13, 2016 at 9:05:06 PM UTC-4, Moritz Klammler wrote: > > > Very briefly, some of us are interested in having a standardized > > function 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 such as gaming and electronic trading. In other words, > > a drop-in replacement for std::function, where all data is on the > > stack. > > Isn't this already possible by using today's `std::function` with a > custom allocator backed by a stack-based array? I'm not clear as to what you mean here. Consider this: std::function a_func() { return []{}; } What would the "stack-based array" equivalent look like? Would it look as reasonable as this? Would it be able to use that nifty guaranteed elision stuff we'll be getting? -- 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/b8ca2bb9-2446-4640-8c40-df6566473f0b%40isocpp.org. ------=_Part_77_800067329.1468462540724 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
On Wednesday, July 13, 2016 at 9:05:06 PM UTC-4, Moritz Kl= ammler wrote:
> Very briefly= , some of us are interested in having a standardized
> function which does not incur an upfront memory allocation to stor= e
> the callable target, instead opting for a compile time specified
> buffer (stack allocated). This has been quite useful in several lo= w
> latency domains such as gaming and electronic trading. In other wo= rds,
> a drop-in replacement for std::function, where all data is on the
> stack.

Isn't this already possible by using today's `std::function` wi= th a
custom allocator backed by a stack-based array?

I&= #39;m not clear as to what you mean here. Consider this:

std::function<void()> a_func()
{
= =C2=A0 ret= urn []{};
}
=
What would the "stack-based array" equivalent look like? Woul= d it look as reasonable as this? Would it be able to use that nifty guarant= eed elision stuff we'll be getting?

--
You received this message because you are subscribed to the Google Groups &= quot;ISO C++ Standard - Future Proposals" group.
To unsubscribe from this group and stop receiving emails from it, send an e= mail to std-proposa= ls+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/b8ca2bb9-2446-4640-8c40-df6566473f0b= %40isocpp.org.
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