220 4643 <87sj17anqh.fsf@euclid.axiomatics.org> article Path: news.gmane.org!not-for-mail From: Gabriel Dos Reis Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Changing lambda scope Date: Mon, 27 May 2013 20:37:26 -0500 Organization: axiomatics.org Lines: 59 Approved: news@gmane.org Message-ID: <87sj17anqh.fsf@euclid.axiomatics.org> References: <90375ba5-8005-47da-9e84-eee151d0ba0a@isocpp.org> <2e120ca5-740b-4301-8a32-8ac5035fa108@isocpp.org> <0df9d0d8-a752-4841-ba02-54780590f722@isocpp.org> <87d2sd5k77.fsf@euclid.axiomatics.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 X-Trace: ger.gmane.org 1369705053 15952 80.91.229.3 (28 May 2013 01:37:33 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 28 May 2013 01:37:33 +0000 (UTC) Cc: std-proposals@isocpp.org To: Nicol Bolas Original-X-From: std-proposals+bncBCSYNQUB2UHRBWUUSCGQKGQEAG2DZBA@isocpp.org Tue May 28 03:37:34 2013 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ie0-f200.google.com ([209.85.223.200]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1Uh8qx-00031x-TB for gclcip-std-proposals@m.gmane.org; Tue, 28 May 2013 03:37:32 +0200 Original-Received: by mail-ie0-f200.google.com with SMTP id 10sf31144820ied.3 for ; Mon, 27 May 2013 18:37:31 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=x-beenthere:from:to:cc:subject:in-reply-to:organization:references :sender:date:message-id:lines:mime-version: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=gArLol/FenWTyReBMfAtXdyjOW9Qh50dyX86uA580tg=; b=D3hVCseRuBWJ4BlSvaph7YsIwb5IV7ZrTTk+ej1yGnPLiTYz/Z8yzEUPvVxaWCGJYg 7WFIX1QijdYBtPJ0+UKUfTqeCDh12K4si+XKuZ1RYdNlE4Xdi+kcS1LPumV9GDTkndHk 6RlS9BO9skuvEZ1XmWoSXvQRbfdbZvPYqSxShqc/u1H+ZQpa3WMMm/kdh8v7XfChlgDH cxzndk2r3A036r//AhXmsvDiYxi+f9ZzV8Web39EY3t1l/rtnX1mBSoIQUZf/rw5t2ep 1PhyJiZaRSwhg9FghxiwFWkFmkmi7D1bFmUjzOEA4QO86uTuis/K+NCRIUVGqtqsp0Xs X-Received: by 10.182.138.101 with SMTP id qp5mr1055582obb.16.1369705050844; Mon, 27 May 2013 18:37:30 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.182.115.202 with SMTP id jq10ls1225977obb.72.gmail; Mon, 27 May 2013 18:37:27 -0700 (PDT) X-Received: by 10.60.178.242 with SMTP id db18mr19155817oec.74.1369705047216; Mon, 27 May 2013 18:37:27 -0700 (PDT) Original-Received: from mail.axiomatics.org ([2600:3c00::f03c:91ff:feae:e0e6]) by mx.google.com with ESMTP id qo7si18341457obb.59.2013.05.27.18.37.27 for ; Mon, 27 May 2013 18:37:27 -0700 (PDT) Received-SPF: neutral (google.com: 2600:3c00::f03c:91ff:feae:e0e6 is neither permitted nor denied by best guess record for domain of gdr@axiomatics.org) client-ip=2600:3c00::f03c:91ff:feae:e0e6; Original-Received: by mail.axiomatics.org (Postfix, from userid 1000) id CB207EBB6; Mon, 27 May 2013 20:37:26 -0500 (CDT) In-Reply-To: (Nicol Bolas's message of "Mon, 27 May 2013 00:19:11 -0700 (PDT)") Original-Sender: gdr@euclid.axiomatics.org Original-Lines: 48 X-Original-Sender: gdr@axiomatics.org X-Original-Authentication-Results: mx.google.com; spf=neutral (google.com: 2600:3c00::f03c:91ff:feae:e0e6 is neither permitted nor denied by best guess record for domain of gdr@axiomatics.org) smtp.mail=gdr@axiomatics.org 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:4643 Archived-At: Nicol Bolas writes: | On Sunday, May 26, 2013 5:40:28 PM UTC-7, Gabriel Dos Reis wrote: | | Zhihao Yuan writes: | | | On Sun, May 26, 2013 at 7:17 PM, Nicol Bolas wrote: | | > A lambda is nothing special; it's just shorthand notation for a type | | > declared at that scope. We shouldn't have special-case language in the | | > standard that says "if the local type is a lambda type, blah blah". | | | | I don't agree. Lambda is special, conceptually, as a language structure. | | It's described in terms of a class / class template does not mean its | | semantics has to be limited by class / class template. | | I tend to agree that a lambda expression is a fundamental language | construct (from semantics point of view), and it is unfortunate that we | somehow think of it in terms of local classes. We shouldn't think of | lambdas in terms of implementation details. | | | Whatever they may be "from semantics point of view", they are still just types. I am afraid I do not understand by what you mean by that sentence. Could you elaborate? | The fact that there's nothing a lambda can do which you can't do yourself is a | strength of C++ lambdas, not a weakness. Again, I am afraid I do not understand this statement. | It allows you to swap a lambda for a | regular class if the lambda gets too complex for the lambda syntax to work. The | class version will have the exact same behavior as the lambda version, modulo | extra features of the class. | | We should not allow lambdas to do anything you couldn't do yourself. We don't | want people overloading on lambdas. We don't want people writing huge, complex | lambdas when a struct definition would be more appropriate, and having I am afraid I do not see how you got from there to here. | different functionality between lambdas and structs would encourage doing this. | However much people may want lambdas to be some unique construct with its own | special rules, C++ shouldn't allow that. | | It's just a class with a operator() overload. We should not pretend that it's | anything but that. -- --- 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. .