220 7048 article Path: news.gmane.org!not-for-mail From: Jeremiah Willcock Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: Unnamed LValues Date: Sat, 5 Oct 2013 15:56:55 -0400 (EDT) Lines: 48 Approved: news@gmane.org Message-ID: References: <0d9b268f-cd3a-4048-a0a3-50cff02b28ce@isocpp.org> <525031B5.80202@wanadoo.fr> <06e15a1f-0f12-408f-b0cd-077669caeb31@isocpp.org> <52503F47.9030308@wanadoo.fr> <525054DD.5070907@wanadoo.fr> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable X-Trace: ger.gmane.org 1381005318 1663 80.91.229.3 (5 Oct 2013 20:35:18 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sat, 5 Oct 2013 20:35:18 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBAABBBPQYGJAKGQEFKUBWEA@isocpp.org Sat Oct 05 22:35:21 2013 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-gg0-f197.google.com ([209.85.161.197]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1VSYZK-0007Eb-Ee for gclcip-std-proposals@m.gmane.org; Sat, 05 Oct 2013 22:35:18 +0200 Original-Received: by mail-gg0-f197.google.com with SMTP id l4sf5894696ggi.0 for ; Sat, 05 Oct 2013 13:35:17 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=date:from:to:subject:in-reply-to:message-id:references:user-agent :mime-version: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 :content-transfer-encoding; bh=XS4F8wteyhtLBy83dnb10oUVUHkZf+p7G68B44fLZ7E=; b=eMJGm+kdTiQ6kYJ4K+j8ylWiLAfoWOAvhwlesTRgC8IlnEa9Qzl5fJsZhkpKENr2jK Eypx5SVc7bhHE+ianld4xaMN4AqLA3DUse5ijgK2rICEOzTmkhGTFDFxJkBsPpnsBLWt 0Gbz5J05ylrcz6BceLF4sAsE8J6TyPAWU/yeDeNK4hj0nrS1Sn14hCj5OaZdcwAn6Trp jWf2DEHKk0MU6g5J/VGlRywfg2KyF4P6gy3IDGxOki9oe3/rDzpbnuKg1FUCQrOwMoh7 ynWkKrfaQ7gQWyTlMAw5Sm+IYNVfJePfQkWTCbvUTIyOrvvgnuUqgX7a98F7jY3i+QFB LCkw== X-Received: by 10.236.117.136 with SMTP id j8mr2273262yhh.18.1381005317527; Sat, 05 Oct 2013 13:35:17 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.49.29.129 with SMTP id k1ls1914103qeh.75.gmail; Sat, 05 Oct 2013 13:35:17 -0700 (PDT) X-Received: by 10.224.137.67 with SMTP id v3mr35416859qat.0.1381005317117; Sat, 05 Oct 2013 13:35:17 -0700 (PDT) Original-Received: by 10.224.129.195 with SMTP id p3msqas; Sat, 5 Oct 2013 12:56:56 -0700 (PDT) X-Received: by 10.236.63.10 with SMTP id z10mr16528953yhc.28.1381003015960; Sat, 05 Oct 2013 12:56:55 -0700 (PDT) Original-Received: from hartman.uits.indiana.edu (belushi.uits.indiana.edu. [129.79.1.188]) by mx.google.com with ESMTP id c66si7801377yhm.284.1969.12.31.16.00.00; Sat, 05 Oct 2013 12:56:55 -0700 (PDT) Received-SPF: neutral (google.com: 129.79.1.188 is neither permitted nor denied by best guess record for domain of jewillco@crest.iu.edu) client-ip=129.79.1.188; X-IronPort-AV: E=Sophos;i="4.90,1040,1371096000"; d="scan'208";a="72607390" Original-Received: from mssg-relay.indiana.edu ([129.79.1.73]) by irpt-internal-relay.indiana.edu with ESMTP; 05 Oct 2013 15:56:55 -0400 Original-Received: from hartman.uits.indiana.edu (belushi.uits.indiana.edu [129.79.1.188]) by mssg-relay.indiana.edu (8.14.7/8.14.4/IU Messaging Team) with ESMTP id r95JutdH008908 for ; Sat, 5 Oct 2013 15:56:55 -0400 X-IronPort-AV: E=Sophos;i="4.90,1040,1371096000"; d="scan'208";a="72228182" Original-Received: from candy.uits.indiana.edu (HELO mail-relay.iu.edu) ([129.79.1.201]) by irpt-internal-relay.indiana.edu with ESMTP; 05 Oct 2013 15:56:55 -0400 Original-Received: from anjie.osl.iu.edu (anjie.osl.iu.edu [129.79.242.161]) (authenticated bits=0) by mail-relay.iu.edu (8.14.7/8.14.4/IU Messaging Team Submission) with ESMTP id r95JutOg007387 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Sat, 5 Oct 2013 15:56:55 -0400 X-X-Sender: jewillco@anjie.osl.iu.edu In-Reply-To: <525054DD.5070907@wanadoo.fr> User-Agent: Alpine 2.03 (LRH 1266 2009-07-14) X-Original-Sender: jewillco@crest.iu.edu X-Original-Authentication-Results: mx.google.com; spf=neutral (google.com: 129.79.1.188 is neither permitted nor denied by best guess record for domain of jewillco@crest.iu.edu) smtp.mail=jewillco@crest.iu.edu 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:7048 Archived-At: On Sat, 5 Oct 2013, Vicente J. Botet Escriba wrote: > Le 05/10/13 19:06, Brent Friedman a =E9crit : >> What functionality do we get by adding new block statements versus the= =20 >> original proposal? Presumably adding new block statements carries much m= ore=20 >> language risk and implementation time, so what are we getting for that= =20 >> extra effort? Unless there's a way to attach with/using to an object=20 >> lifetime, it would seem to be even less powerful. > My post contained two proposals. let-in and anonymous variables. > I find somewhere unfortunately to be forced to add an scope > > { > RAI r(...) > return f(); > } // ~RAI > > With a let-in statement we ca have just > > // LET RAI r(...) IN return f(); > RAI r(...) : return f(); > > Vicente The other advantage of a scope statement is for macros that define new=20 variables (think of BOOST_FOREACH, even though that has been replaced by a= =20 language feature now). The alternative techniques using single-iteration= =20 for loops (often nested, and that prevent "break" and "continue" inside=20 the declaration block) are much more complicated than having a let-in=20 statement. -- Jeremiah Willcock --=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/. .