220 4626 article Path: news.gmane.org!not-for-mail From: Ville Voutilainen Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: Changing lambda scope Date: Mon, 27 May 2013 15:31:24 +0300 Lines: 105 Approved: news@gmane.org Message-ID: References: <01190eaa-6223-4d3c-a9d3-b0d850aab98e@isocpp.org> <35af8d3d-8ed6-441c-94d0-b898711190b1@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary=089e0102f736a62d9c04ddb25385 X-Trace: ger.gmane.org 1369657888 31710 80.91.229.3 (27 May 2013 12:31:28 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Mon, 27 May 2013 12:31:28 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBC5JHI7A7ALRBHFERWGQKGQEEPYNRJI@isocpp.org Mon May 27 14:31:28 2013 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-qa0-f70.google.com ([209.85.216.70]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1UgwaE-00021S-3w for gclcip-std-proposals@m.gmane.org; Mon, 27 May 2013 14:31:26 +0200 Original-Received: by mail-qa0-f70.google.com with SMTP id o13sf2808115qaj.1 for ; Mon, 27 May 2013 05:31:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=x-beenthere:mime-version:in-reply-to:references:date:message-id :subject:from:to:x-original-sender:x-original-authentication-results :reply-to:precedence:mailing-list:list-id:x-google-group-id :list-post:list-help:list-archive:list-subscribe:list-unsubscribe :content-type; bh=Fw0IWDoxeXMwir7CTy+HXGnRM0SwcWTtwZaY3ikSGiM=; b=0ofeF10TJubkBpLYj5R3OKUgzMotugMx5JOvewspzSt7cuxMb+Dh5OvXPSV3mQR6Dz Bln/lEYHTUZZ0Yn7lucFTFoAzWJFcP+Elzk0xbMnoitUGeyIna8K646l7el+OycxCVDJ eZG9QJ07BsFM1auyY6FNNtSC8cl6gCVTBA/Q+Qgw8Ld08fTDokpU6oMCQLNinW23Llug aXrhSX6z4i8x8M5L6L2QPJ3L2MZ207u3265W9wDMGIfKQuYk/O0JPhdTYDe9Vhyy5M1A gy2/8nG0sWEb6JSCtACaJFo1FKIpcC03bQbAa7MeEMKEhPRSFNl7owhqLqZ2/1qhtS7F FljA== X-Received: by 10.236.93.116 with SMTP id k80mr14294850yhf.32.1369657885299; Mon, 27 May 2013 05:31:25 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.49.41.7 with SMTP id b7ls2746090qel.12.gmail; Mon, 27 May 2013 05:31:24 -0700 (PDT) X-Received: by 10.229.170.18 with SMTP id b18mr33000qcz.5.1369657884265; Mon, 27 May 2013 05:31:24 -0700 (PDT) Original-Received: from mail-qa0-x232.google.com (mail-qa0-x232.google.com [2607:f8b0:400d:c00::232]) by mx.google.com with ESMTPS id gt9si24229913qab.16.2013.05.27.05.31.24 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Mon, 27 May 2013 05:31:24 -0700 (PDT) Received-SPF: pass (google.com: domain of ville.voutilainen@gmail.com designates 2607:f8b0:400d:c00::232 as permitted sender) client-ip=2607:f8b0:400d:c00::232; Original-Received: by mail-qa0-f50.google.com with SMTP id bn16so949825qab.2 for ; Mon, 27 May 2013 05:31:24 -0700 (PDT) X-Received: by 10.224.146.66 with SMTP id g2mr6999994qav.50.1369657884150; Mon, 27 May 2013 05:31:24 -0700 (PDT) Original-Received: by 10.224.174.143 with HTTP; Mon, 27 May 2013 05:31:24 -0700 (PDT) In-Reply-To: <35af8d3d-8ed6-441c-94d0-b898711190b1@isocpp.org> X-Original-Sender: ville.voutilainen@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of ville.voutilainen@gmail.com designates 2607:f8b0:400d:c00::232 as permitted sender) smtp.mail=ville.voutilainen@gmail.com; dkim=pass header.i=@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:4626 Archived-At: --089e0102f736a62d9c04ddb25385 Content-Type: text/plain; charset=ISO-8859-1 On 27 May 2013 15:18, wrote: > > You can return a lambda or a local class from a lambda in C++11, so that >> doesn't count as an excuse for noticing this now because >> we can return local types from a non-lambda in C++14. >> > > Sort of. You can return it from a lambda but you can't return it out of > the enclosing non-lambda function scope. The only way to pass it out of the > *namespace*, which is what matters, is to pass it into a template, which > is what I did with my example. > I'm not sure I quite follow. namespace N { auto x = [](){ return [](){std::cout << "In the inner lambda" << std::endl;}; }; } int main() { auto y = N::x; auto z = y(); z(); } The inner lambda got passed out of the namespace just fine, and that works in C++11. > > By the way, the language as-is seems deeply flawed. Only a singly-nested > class has an associated namespace; nest a class inside a nested class and > it becomes disconnected from its namespace. > Interesting. -- --- 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. 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On 27 May 2013 15:18, <potswa@gmail.com> wrote:
<= blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-l= eft:1px solid rgb(204,204,204);padding-left:1ex">

You can return a lambda = or a local class from a lambda in C++11, so that doesn't count as an ex= cuse for noticing this now because
we can return local types from a non-lambda in C++14.
=

Sort of. You can return it from a lambda = but you can't return it out of the enclosing non-lambda function scope.= The only way to pass it out of the namespace, which is what matters= , is to pass it into a template, which is what I did with my example.

I'm not sure I quite follow.
=
namespace N {
=A0=A0=A0 auto x =3D [](){
=A0 =A0 =A0=A0 return=A0= [](){std::cout << "In the inner lambda" << std::endl= ;};
=A0=A0=A0 };
}

int main()
{
=A0=A0=A0 auto y =3D N::x;
=A0=A0=A0 auto= z =3D y();
=A0=A0=A0 z();
}

The inner lambda got = passed out of the namespace just fine, and that works in C++11.
=A0
<= /div>

By the way, the language as-is seems deeply flawed. Only a singly-= nested class has an associated namespace; nest a class inside a nested clas= s and it becomes disconnected from its namespace.

Interesting.

--
 
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