220 26943 <2813901a-dc9d-4c4f-ae07-21a16c0b0da2@isocpp.org> 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 19:25:40 -0700 (PDT) Lines: 112 Approved: news@gmane.org Message-ID: <2813901a-dc9d-4c4f-ae07-21a16c0b0da2@isocpp.org> References: Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_14_2089011895.1468463141100" X-Trace: ger.gmane.org 1468463156 6306 80.91.229.3 (14 Jul 2016 02:25:56 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 14 Jul 2016 02:25:56 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBCEKFTV6ZUMBBJXQTO6AKGQE7BK3BPI@isocpp.org Thu Jul 14 04:25:48 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-pf0-f199.google.com ([209.85.192.199]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1bNWLQ-0005i7-Jh for gclcip-std-proposals@m.gmane.org; Thu, 14 Jul 2016 04:25:44 +0200 Original-Received: by mail-pf0-f199.google.com with SMTP id y134sf75574265pfg.1 for ; Wed, 13 Jul 2016 19:25:44 -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=+bVlfbtyyuqkinYExjoh4iKyahZm9XGBkcCNG1cvilo=; b=p0WeqVRJ4Izar6v9gLjuZzXM0hSyISfQVrzBq52qPIU2L1yOqWBf40P3WykBMzfRgM c/uwEStkdmZOQoPjAsEWQ+lq2c/GXRAwsqWW2ekX5l5Wd3KPZl5XpJcIgaCA1WoOb4ei x01cZiTjQeLyV904gvJjDr2PxRF6WdYyd0FaECb1YEMdsrKuuPoHEAnZkVDZYCr+dR8/ iI9igv+UrOZjWg1WMymIcRFQIqqoRl7KOgI9iVznxTFRPyXjFEyp0HkFq9/GNSkq4yX7 a1Hxdd235H9/jx7dSXo/WdHZfrF/ElByUI1FHQp21/WLPWraQwUzn7/Os0HY9yJFAYyf VFZw== 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=+bVlfbtyyuqkinYExjoh4iKyahZm9XGBkcCNG1cvilo=; b=dHO4oJCkbNMTL1DrsnZ42rOEsVaQUNNMhiqcI/nHPyZxCEz6B611Cd4ObfOyVqEJni b3SxjRgpSPjrzxuu2r+z99Dsv0Yx5usFXe5CzZbePxuf4X63ByCYb+8moFDFneDC2Crv /z59UwtIYjv9C8J+Xo9g9SHubSz+ZYAjaBsPJJfNgSTLnB0vA7metT1OCGVdcpsNoj/G IcOPTuiJPJQXJPR1yfgAQjT6WNHpjhs8H9WaxZqH02cgtUgpLXiT5QJd407+edC9C7KI H0RVWoV5MCRYLjYvPZWA6I6fadz32rAsr25zwV+IeSWd80BWrIk+OE28fq7IUIwVpFyo TafA== 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=+bVlfbtyyuqkinYExjoh4iKyahZm9XGBkcCNG1cvilo=; b=bYNueUU70zEtjJjt2zYBwm5fMyg2qH26bWIUpj8RbTw8aTmrV948sznvJ2CeMDkhV1 TJTh3whNPNQ+I3Yw2Q8tWgru/Z5NGw6czMKSvVF49uqfomcrMAY1XllgBb65FwRIFL60 JyLSRC6kliLCNk1FgjmzjcgwZilYPYSCBUOkgQ9t5NKcNjXROrNDtXMunA1yUftzkttU 1FMl9SyhIdJuJk1zNsICLiCk1LYtV0WOIVrlw//GNvZK/BfD4v4xFEPyO+oW1Kj1pRCy D4mUY43ELWcxHy9ULFH3SKFms0+DnYfloJIMyjK6D8yfrENwqvaTptqKzqIEAXAM8VVk hdlQ== X-Gm-Message-State: ALyK8tIjkQ1fAKd8yDM/kRcNCnhdDGP/bw+ivzXOyYy14fxfHxZKwXjgjCIJtXNPslFM6Q== X-Received: by 10.66.253.2 with SMTP id zw2mr8678475pac.43.1468463143433; Wed, 13 Jul 2016 19:25:43 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.107.18.224 with SMTP id 93ls229352ios.19.gmail; Wed, 13 Jul 2016 19:25:41 -0700 (PDT) X-Received: by 10.36.57.15 with SMTP id l15mr1146867ita.7.1468463141926; Wed, 13 Jul 2016 19:25:41 -0700 (PDT) In-Reply-To: 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:26943 Archived-At: ------=_Part_14_2089011895.1468463141100 Content-Type: multipart/alternative; boundary="----=_Part_15_1052940931.1468463141100" ------=_Part_15_1052940931.1468463141100 Content-Type: text/plain; charset=UTF-8 First, would it be possible to make this proposal available via a PDF *not* hosted on GitHub? Like maybe on a github.io page or something, where I can view it in my browser instead of having to download it? Next, I don't believe something like this belongs in the standard. I'm not saying that it isn't a useful class. But its utility is *really* special case. Much like a string with a user-specified SSO size and so forth. Not a bad idea, but just not good for the standard. I really think it would be a good idea to have some form of "special case/low level/etc TS" for these kinds of types. Like the library fundamentals TS, but without the expectation that it would ever go into the standard wholesale. As to the idea itself... I'm not really sure about it. My main concern is this: std::inplace_function func() { return [x = 12]() {return x;}; } What can I set `VALUE` to which will *guarantee* that this code compiles? Because I don't think the standard gives us a way to do that. Oh sure, from a practical perspective, we can make some guesses about the size of the lambda type. But even so, it's not clear that any particular `VALUE` would permit compilation. -- 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/2813901a-dc9d-4c4f-ae07-21a16c0b0da2%40isocpp.org. ------=_Part_15_1052940931.1468463141100 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
First, would it be possible to make this proposal availabl= e via a PDF not hosted on GitHub? Like maybe on a github.io page or something, where I=20 can view it in my browser instead of having to download it?

Next, I = don't believe something like this belongs in the standard. I'm not = saying that it isn't a useful class. But its utility is really s= pecial case. Much like a string with a user-specified SSO size and so forth= .. Not a bad idea, but just not good for the standard.

I really think= it would be a good idea to have some form of "special case/low level/= etc TS" for these kinds of types. Like the library fundamentals TS, bu= t without the expectation that it would ever go into the standard wholesale= ..

As to the idea itself... I'm not really sure about it. My main= concern is this:

=
std::in= place_function<in= t(), VALUE> func()
{
=C2=A0 return [x =3D 12]() {return x;};
}=

What can I set `VALUE` to which will guara= ntee that this code compiles? Because I don't think the standard gi= ves us a way to do that. Oh sure, from a practical perspective, we can make= some guesses about the size of the lambda type. But even so, it's not = clear that any particular `VALUE` would permit compilation.

--
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/2813901a-dc9d-4c4f-ae07-21a16c0b0da2= %40isocpp.org.
------=_Part_15_1052940931.1468463141100-- ------=_Part_14_2089011895.1468463141100-- .