220 4609 article Path: news.gmane.org!not-for-mail From: Richard Smith Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Changing lambda scope Date: Sun, 26 May 2013 15:30:36 -0700 Lines: 173 Approved: news@gmane.org Message-ID: 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=047d7bacbcceb6440f04dda69480 X-Trace: ger.gmane.org 1369607439 29233 80.91.229.3 (26 May 2013 22:30:39 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sun, 26 May 2013 22:30:39 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDVNBJG4YAIBBDM2RKGQKGQEONCDIHA@isocpp.org Mon May 27 00:30:39 2013 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-wi0-f200.google.com ([209.85.212.200]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1UgjSY-0000eu-NT for gclcip-std-proposals@m.gmane.org; Mon, 27 May 2013 00:30:38 +0200 Original-Received: by mail-wi0-f200.google.com with SMTP id c10sf1375427wiw.7 for ; Sun, 26 May 2013 15:30:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=x-beenthere:mime-version:sender: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=eIxhsR71QWnKjfuZz7cjQRT+MTWjucOYHfwXojRzPh0=; b=kTz+wOQ7mHAtdDAojlA51r2Y9kLp+h5PaJ/kfUw2ApgR9xlaKfKqUQr1q4KyYYfXT1 edSzKaWw/Eosp6t9Z1E2Rf3yzR4eNaUPmj8OtqB0aOdYYbuYhSvq8YTnus7LQ64sHTdc QlLhJFz9D0U5P287s5ZB9JbBRK62JJVKYjeZQo6k15CvMRmYU6RywFRACXKX+C1I+ae9 6DsGWWs62wQswbzWe+1EK+e3oYd1+e3kgfnm7FUrAQfVunahMD3JG3qnPJd7ULi7FnQa fBZ1NpyKH1ad3/+GQQbKQR+Vz4W8SkSdNY9lrEog6ysjqKESc1BAva+ok/jt4AgE8PSW lUmg== X-Received: by 10.180.76.76 with SMTP id i12mr2915234wiw.6.1369607438188; Sun, 26 May 2013 15:30:38 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.180.109.65 with SMTP id hq1ls713751wib.42.gmail; Sun, 26 May 2013 15:30:37 -0700 (PDT) X-Received: by 10.180.184.75 with SMTP id es11mr6257172wic.38.1369607437294; Sun, 26 May 2013 15:30:37 -0700 (PDT) Original-Received: from mail-ve0-x22d.google.com (mail-ve0-x22d.google.com [2607:f8b0:400c:c01::22d]) by mx.google.com with ESMTPS id ez7si3398524wjd.198.2013.05.26.15.30.36 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Sun, 26 May 2013 15:30:37 -0700 (PDT) Received-SPF: pass (google.com: domain of metafoo@gmail.com designates 2607:f8b0:400c:c01::22d as permitted sender) client-ip=2607:f8b0:400c:c01::22d; Original-Received: by mail-ve0-f173.google.com with SMTP id cy12so4723453veb.32 for ; Sun, 26 May 2013 15:30:36 -0700 (PDT) X-Received: by 10.58.234.134 with SMTP id ue6mr13916769vec.20.1369607436118; Sun, 26 May 2013 15:30:36 -0700 (PDT) Original-Sender: metafoo@gmail.com Original-Received: by 10.58.223.207 with HTTP; Sun, 26 May 2013 15:30:36 -0700 (PDT) In-Reply-To: X-Original-Sender: richard@metafoo.co.uk X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of metafoo@gmail.com designates 2607:f8b0:400c:c01::22d as permitted sender) smtp.mail=metafoo@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:4609 Archived-At: --047d7bacbcceb6440f04dda69480 Content-Type: text/plain; charset=ISO-8859-1 On Sun, May 26, 2013 at 9:01 AM, Ville Voutilainen < ville.voutilainen@gmail.com> wrote: > > > > On 26 May 2013 17:50, DeadMG wrote: > >> Sure. Consider >> >> namespace range { >> template auto operator|(L l, R r) { >> return r(std::move(l)); >> } >> template auto map(T t) { >> return [=](auto range) { >> auto var = range(); >> if (var) return optional> ))>::type>(t(*var)); >> return std::none; >> }; >> } >> } >> int main() { >> something >> | range::map([]...) >> | range::map([]...) >> etc >> } >> >> 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. >> >> >> >> > Thanks, that looks very reasonable. I'll ask Core for the status quo > rationale as a first step. > Should this apply only to lambdas, or to all local classes? -- --- 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. --047d7bacbcceb6440f04dda69480 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On Sun, May 26, 2013 at 9:01 AM, Ville Voutilainen <ville.voutil= ainen@gmail.com> wrote:



On 26 May 2013 17:50, DeadMG &l= t;wolfeinstein@= gmail.com> wrote:
Sure. Consider

namespace range <= span style=3D"color:#660">{
=A0 =A0 template<typename R,<= /span> typename L> auto operator|(L l, R r) {
=A0 =A0 =A0 =A0 return r(std::move(l<= /span>));
=A0 =A0 }
=A0 =A0 = template<typename T> auto map(T t) {<= /span>
=A0 =A0 =A0 =A0 return [=3D](auto range) {
=A0 =A0 =A0 =A0 =A0 =A0 auto= var =3D range();
=A0 =A0 =A0 =A0 =A0 =A0 if <= /span>(var) return optional<typename std::decay<decltype(t(*var))>::type>(t(*var));
=A0 =A0 =A0 =A0 =A0 =A0 return std::none;
=A0 =A0 =A0 =A0 };
=A0 =A0 }
}
int<= /span> main() <= span style=3D"color:#660">{
=A0 =A0 something
=A0 =A0 =A0 =A0 | range::map= ([]...)
=A0 =A0 =A0 =A0 <= span style=3D"color:#660">| range::map([]...)
=A0 =A0 =A0 =A0 etc
}

It's part of a range design I am working o= n. I have implemented everything I need but the lambda ADL problem means th= at I can't use lambdas when I should be able to, because the range-comb= ine operator| can't be found.




Thanks, that loo= ks very reasonable. I'll ask Core for the status quo rationale as a fir= st step.=A0

Should = this apply only to lambdas, or to all local classes?=A0

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