220 4793 <943b7d81-5118-4dab-9ed2-017412abacc8@isocpp.org> article Path: news.gmane.org!not-for-mail From: Mikhail Semenov Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Changing lambda scope Date: Sun, 2 Jun 2013 08:39:09 -0700 (PDT) Lines: 111 Approved: news@gmane.org Message-ID: <943b7d81-5118-4dab-9ed2-017412abacc8@isocpp.org> References: <90375ba5-8005-47da-9e84-eee151d0ba0a@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_233_21487430.1370187549997" X-Trace: ger.gmane.org 1370187553 20931 80.91.229.3 (2 Jun 2013 15:39:13 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sun, 2 Jun 2013 15:39:13 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDC55PNFRYGRBH6OVWGQKGQECN3PT3I@isocpp.org Sun Jun 02 17:39:14 2013 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-gg0-f198.google.com ([209.85.161.198]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1UjANE-0002pP-F7 for gclcip-std-proposals@m.gmane.org; Sun, 02 Jun 2013 17:39:12 +0200 Original-Received: by mail-gg0-f198.google.com with SMTP id p1sf3742411ggn.9 for ; Sun, 02 Jun 2013 08:39:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=x-beenthere:date:from:to:message-id:in-reply-to:references:subject :mime-version:x-original-sender:reply-to:precedence:mailing-list :list-id:x-google-group-id:list-post:list-help:list-archive :list-subscribe:list-unsubscribe:content-type; bh=AgxGsguEucn1o3imaqHoNLLr1m/uEQ4vplrcuBS8Zss=; b=ZkFrGdOFWW6lhW0vW9e7XDTaxPCmnk3VrDx1gyoxZK4x1V+diFPCfFPjUGKQy4ks1U omFdD5I1fORRAHZFgkcxuBKy8rbQVlzU8kGjTVtjt7Rnoec7Z3OILSl4/XNqqHtZEiUt 3V9mXqa2oym5XRo/L2JFEQp89qmm2zxmZhylDfmkmopujOjuZOxdGahdMKhx+dG+7vj7 ijDrSESa0WiQ53AAIqWcq1Wq8Mvt6vrN7kPTAiWAN7KxZ9e9hNFTUG5Rvs6I5vxm+lLh 2FZx5qBM+Lb7JnnNHBWz3nJowOzh66BKddge6d2rUK/mSkUnq2nn7nph+yq+Nq05GBUS M6RQ== X-Received: by 10.224.36.66 with SMTP id s2mr11717987qad.6.1370187551569; Sun, 02 Jun 2013 08:39:11 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.49.82.110 with SMTP id h14ls1689231qey.88.gmail; Sun, 02 Jun 2013 08:39:10 -0700 (PDT) X-Received: by 10.49.107.234 with SMTP id hf10mr1424577qeb.21.1370187550375; Sun, 02 Jun 2013 08:39:10 -0700 (PDT) In-Reply-To: <90375ba5-8005-47da-9e84-eee151d0ba0a@isocpp.org> X-Original-Sender: mikhailsemenov1957@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:4793 Archived-At: ------=_Part_233_21487430.1370187549997 Content-Type: text/plain; charset=ISO-8859-1 This is not exactly what you wanted, but the following works: #include #include namespace range { template auto operator|(L l, R r) -> L { return l+r; } template auto map(T t) //-> std::function // GCC 4.8.0 accepts without the result type { return [=](bool range) -> int { if (range) return t.i; return 0; }; } } struct A { int i; A(int i1):i(i1) {} }; int main() { int something = 10; A a1(5); A a2(6); int k = something | range::map(a1)(true) | range::map(a2)(false); std::cout << k << std::endl; // 15 is the printed result } > It's part of a range design I am working on. I have implemented everything > I need but the lambda ADL problem means that I can't use lambdas when I > should be able to, because the range-combine operator| can't be found. > -- --- 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/?hl=en. ------=_Part_233_21487430.1370187549997 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
This is not exactly what you wanted, but the following works:
 
#include <iostre= am>
#include <functional>
namespace range
{
    template<ty= pename R, typename L> auto operator|(L l, R r) -> L
  &n= bsp; {
         return l+r; = ;      
    }
 &nb= sp;  template<typename T> auto map(T t) //-> std::function<= ;int(bool)> // GCC 4.8.0 accepts without the result type
&n= bsp;   {
        return [= =3D](bool range) -> int
        {<= br>            if (r= ange) return t.i;
         =    return 0;
        };
=     }
}
struct A
{
   int i;
   A(int i1):i(i1) {= }
};
int main() {
    int something =3D 10;
    A a1(= 5);
    A a2(6);
    int k =3D
 = ;   something
        | ran= ge::map(a1)(true)
        | range::ma= p(a2)(false);
    std::cout << k << std::endl= ; // 15 is the printed result      
= }


 
It= 's part of a range design I am working on. I have implemented everything I = need but the lambda ADL problem means that I can't use lambdas when I shoul= d be able to, because the range-combine operator| can't be found.

--
 
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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-pro= posals/?hl=3Den.
 
 
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