220 7743 article Path: news.gmane.org!not-for-mail From: "Billy O'Neal" Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: A proposal to add lambda/function traits to the STL Date: Wed, 13 Nov 2013 13:27:15 -0800 Lines: 233 Approved: news@gmane.org Message-ID: References: <203889a9-743f-4083-ba9b-fd15506b2e86@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary=089e013d0db0724dca04eb15a3ee X-Trace: ger.gmane.org 1384378074 4716 80.91.229.3 (13 Nov 2013 21:27:54 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 13 Nov 2013 21:27:54 +0000 (UTC) To: std-proposals Original-X-From: std-proposals+bncBDKLBLVE6ADBBXG5R6KAKGQEPPV5HAQ@isocpp.org Wed Nov 13 22:28:01 2013 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-pb0-f69.google.com ([209.85.160.69]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1Vghyg-0003m8-Cy for gclcip-std-proposals@m.gmane.org; Wed, 13 Nov 2013 22:27:58 +0100 Original-Received: by mail-pb0-f69.google.com with SMTP id md4sf1961217pbc.8 for ; Wed, 13 Nov 2013 13:27:57 -0800 (PST) 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:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:list-post:list-help:list-archive:list-subscribe :list-unsubscribe:content-type; bh=luYm37bZRQoJnbFuaP/fGTR1qn+G2cKaxX8Wl/u20W8=; b=KrBQRP+Q1xBcPwXLqBywNSK6Qz75R46ufrozLnyNCQf+WHO3iB3yqKGixnoofdIg9B MNS6r9ze0DdkXg6b6ps+yATzp1NaB9e9yJVpBrYHjs5uOuQnCHBhNLOivl3ePghf8B12 fq95R3ITkoyXBrkvqRGsdEmFusnRWe6jbl5iOYBY8LhL2adQnSx18JKbum7uj0jz3q/j qHDBZEmnKMZCULuYC9ocxPzAd5iVTr1pUov72kicEo2CjEF/4XGzjfUwOA/k7M3kUSjv N3OU9JjsYBrTok1UbTVHQPcpeqCRHpqyTI2my7tMsqbsMy87tJOHESBmdOR/MQQziuWz 4C4w== X-Gm-Message-State: ALoCoQnOqwl0fVaJQuhWYZG2GRD6IoBFVxVJd6TAltEZZND+BHCFJMeQdv0C3YI1rqLJbRGEx2g5 X-Received: by 10.66.164.41 with SMTP id yn9mr14564150pab.7.1384378077202; Wed, 13 Nov 2013 13:27:57 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.49.119.9 with SMTP id kq9ls693162qeb.48.gmail; Wed, 13 Nov 2013 13:27:56 -0800 (PST) X-Received: by 10.236.123.144 with SMTP id v16mr457972yhh.213.1384378076485; Wed, 13 Nov 2013 13:27:56 -0800 (PST) Original-Received: from mail-oa0-x22d.google.com (mail-oa0-x22d.google.com [2607:f8b0:4003:c02::22d]) by mx.google.com with ESMTPS id k66si3717610yhj.95.2013.11.13.13.27.56 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 13 Nov 2013 13:27:56 -0800 (PST) Received-SPF: pass (google.com: domain of billy.oneal@gmail.com designates 2607:f8b0:4003:c02::22d as permitted sender) client-ip=2607:f8b0:4003:c02::22d; Original-Received: by mail-oa0-f45.google.com with SMTP id m1so1204463oag.32 for ; Wed, 13 Nov 2013 13:27:56 -0800 (PST) X-Received: by 10.182.113.195 with SMTP id ja3mr19434674obb.46.1384378075856; Wed, 13 Nov 2013 13:27:55 -0800 (PST) Original-Received: by 10.182.87.37 with HTTP; Wed, 13 Nov 2013 13:27:15 -0800 (PST) In-Reply-To: X-Original-Sender: billy.oneal@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of billy.oneal@gmail.com designates 2607:f8b0:4003:c02::22d as permitted sender) smtp.mail=billy.oneal@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-Google-Group-Id: 399137483710 List-Post: , List-Help: , List-Archive: List-Subscribe: , List-Unsubscribe: , Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:7743 Archived-At: --089e013d0db0724dca04eb15a3ee Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Not quite -- this detection fails for other stateless functions, e.g. struct MyFunctor { // Stateless void operator()(int x) { // ... } }; If you want to test whether the thing is convertible to a function pointer, use std::is_convertible-- it already exists and answers the question you really are asking here. Billy O'Neal https://github.com/BillyONeal/ http://stackoverflow.com/users/82320/billy-oneal Malware Response Instructor - BleepingComputer.com On Wed, Nov 13, 2013 at 1:23 PM, wrote: > It means that its capture list is empty. This can be useful since a lambd= a > without a capture list can be converted to a function pointer. > > Le mercredi 13 novembre 2013 22:11:15 UTC+1, Billy O'Neal a =E9crit : >> >> What does it mean that a lambda is stateless? >> >> Billy O'Neal >> https://github.com/BillyONeal/ >> http://stackoverflow.com/users/82320/billy-oneal >> Malware Response Instructor - BleepingComputer.com >> >> >> On Wed, Nov 13, 2013 at 1:09 PM, wrote: >> >>> Something that came up today on StackOverflow: >>> http://stackoverflow.com/questions/19961873/test-if-a- >>> lambda-is-stateless >>> >>> You might want to add such a trait to your proposal to check whether a >>> lambda is stateless :) >>> >>> Le mercredi 6 novembre 2013 19:35:18 UTC+1, Emil 'Skeen' Madsen a =E9cr= it : >>>> >>>> I just finished writing the first draft of my first proposal ever. >>>> And before submitting it, I'd like to discuss the matter at hand, and >>>> the proposal at this forum. >>>> >>>> The proposal is about adding traits, to determine a lambdas return and >>>> argument type(s) at compile time, to the standard library. >>>> >>>> Have a look, >>>> I'm open to all kinds of criticism and feedback :) >>>> >>>> // Emil 'Skeen' Madsen. >>>> >>> -- >>> >>> --- >>> 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-proposal...@isocpp.org. >>> To post to this group, send email to std-pr...@isocpp.org. >>> >>> Visit this group at http://groups.google.com/a/isocpp.org/group/std- >>> proposals/. >>> >> >> -- > > --- > 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/. > --=20 ---=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. Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposa= ls/. --089e013d0db0724dca04eb15a3ee Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
Not quite -- this detection fails for other stateless= functions, e.g.
=A0
struct MyFunctor
{
=A0=A0=A0 // Stateless
=A0=A0=A0 void opera= tor()(int x)
=A0=A0=A0 {
=A0=A0=A0=A0=A0=A0=A0 // ...
=A0=A0=A0 }
};
=
If you want to test whether the thing is convertible to a functi= on pointer, use std::is_convertible -- it already exists and answers the questio= n you really are asking here.

Billy O'Neal
Malware Response Instructor - BleepingComputer.com


On Wed, Nov 13, 2013 at 1:23 PM, <mo= rwenn29@gmail.com> wrote:
It means that its capture list is empty. This can be usefu= l since a lambda without a capture list can be converted to a function poin= ter.

Le mercredi 13 novembre 2013 22:11:15 UTC+1, Billy O'Neal a= =E9crit=A0:
What does it mean that a lambda is state= less?

Billy O'Neal
<= div>Malware Response Instructor - BleepingComputer.com


On Wed, Nov 13, = 2013 at 1:09 PM, <morw...@gmail.com>= wrote:
Something that came up today on StackOverflow: http://stackoverflow.com/questions/19961873/test-i= f-a-lambda-is-stateless

You might want to add such a trait to your proposal to check whether a = lambda is stateless :)

Le mercredi 6 novembre 2013 19:35:18 UTC+1, E= mil 'Skeen' Madsen a =E9crit=A0:
I just finished writing the first draft of my first propos= al ever.
And before submitting it, I'd like to discuss the matter at= hand, and the proposal at this forum.

The proposal is about adding = traits, to determine a lambdas return and argument type(s) at compile time,= to the standard library.

Have a look,
I'm open to all kinds of criticism and feedback :)<= br>
// Emil 'Skeen' Madsen.

--
=A0
---
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-proposal...@isocpp.org.
To post to this group, send email to std-pr...@isocpp.org.

Visit this group at http://groups.google.com/a/isocpp.= org/group/std-proposals/.

--
=A0
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You received this message because you are subscribed to the Google Groups &= quot;ISO C++ Standard - Future Proposals" group.
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