220 17430 <0c39ed29-d389-4894-bc65-71a9bb79cbe5@isocpp.org> article Path: news.gmane.org!not-for-mail From: Avi Kivity Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Proposal: lambda move capture Date: Sun, 19 Apr 2015 07:06:02 -0700 (PDT) Lines: 65 Approved: news@gmane.org Message-ID: <0c39ed29-d389-4894-bc65-71a9bb79cbe5@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_2138_123544281.1429452362233" X-Trace: ger.gmane.org 1429452366 1858 80.91.229.3 (19 Apr 2015 14:06:06 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sun, 19 Apr 2015 14:06:06 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDHJFOWD7YCRBS7MZ2UQKGQEX4VWIFA@isocpp.org Sun Apr 19 16:06:06 2015 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-pd0-f197.google.com ([209.85.192.197]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1YjprJ-0007Zb-HO for gclcip-std-proposals@m.gmane.org; Sun, 19 Apr 2015 16:06:05 +0200 Original-Received: by pdbqd1 with SMTP id qd1sf250217754pdb.1 for ; Sun, 19 Apr 2015 07:06:03 -0700 (PDT) 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:subject:mime-version :content-type:x-original-sender:reply-to:precedence:mailing-list :list-id:list-post:list-help:list-archive:list-subscribe :list-unsubscribe; bh=fFpioEtEQbWYIXpOnq2FDgbm770tAUNhC6OkJuXU7XU=; b=YXVfg+af2Y9GfB7egeS8svhA6JJZzd+aJRrB7dpmjsatZ/an7yXeG1L77oP3aN3BH3 f4t6S++9qEHx4bz6Wi4cw3vz2WYdrPy6+4sdKMiMttngyha1NdSObz2kp2KvhK2Jbobw OGMCLAJpE4ZQAvBv2AZ42Vb7xuLTwwlP75xwNY5iKRH+tcuGvwAImU4hj1Rhosl4ECkR Rr+IKztVWd0z3TYvrczxNnx5tLQPiLWYB+tyAJyHJuZ9VCGuUf1HJgYd175wqndRWlax U7Tjydf/b1Uz/dfR1nHLwwmzdg0FrJpidp+59y1W7pv0SVUIn+Jbux0JjhaFDs2O21Bq gdOQ== X-Gm-Message-State: ALoCoQn0b9HAB8XB48qvxZIGXduphFk7SYKZ+zcJnAsc8UpSDvSuiNz60h8acaQWzdl0XPDX+i8q X-Received: by 10.66.218.10 with SMTP id pc10mr16172833pac.13.1429452363875; Sun, 19 Apr 2015 07:06:03 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.140.109.230 with SMTP id l93ls2359028qgf.39.gmail; Sun, 19 Apr 2015 07:06:03 -0700 (PDT) X-Received: by 10.140.98.175 with SMTP id o44mr157107qge.33.1429452363062; Sun, 19 Apr 2015 07:06:03 -0700 (PDT) X-Original-Sender: avi@cloudius-systems.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:17430 Archived-At: ------=_Part_2138_123544281.1429452362233 Content-Type: multipart/alternative; boundary="----=_Part_2139_1939527765.1429452362234" ------=_Part_2139_1939527765.1429452362234 Content-Type: text/plain; charset=UTF-8 Lambdas currently support three styles of capture: 1. Init capture (fully generic) [x = expression] 2. Copy capture: [x], equivalent to [x = x] 3. Reference capture: [&x], roughly equivalent to [x = std::ref(x)] As I find myself typing [x = std::move(x)] more and more, I propose to support a fourth style: 4. Move capture: [&&x], equivalent to [x = std::move(x)] This would be very useful for move-only types such as unique_ptr<>. (the idea has been proposed before on the comp.std.c++ newsgroup) -- --- 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/. ------=_Part_2139_1939527765.1429452362234 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Lambdas currently support three styles of capture:
1. Init capture (fully generic) [x =3D expression]
2.= Copy capture: [x], equivalent to [x =3D x]
3. Reference capture:= [&x], roughly equivalent to [x =3D std::ref(x)]

As I find myself typing [x =3D std::move(x)] more and more, I propose to= support a fourth style:

4. Move capture: [&&a= mp;x], equivalent to [x =3D std::move(x)]

This wou= ld be very useful for move-only types such as unique_ptr<>.

(the idea has been proposed before on the comp.std.c++ news= group)


--

---
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.
Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposals/<= /a>.
------=_Part_2139_1939527765.1429452362234-- ------=_Part_2138_123544281.1429452362233-- .