220 10593 <20140509221552.GA32099@sara.home> article Path: news.gmane.org!not-for-mail From: Magnus Fromreide Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Forward declaring names Date: Sat, 10 May 2014 00:15:52 +0200 Lines: 57 Approved: news@gmane.org Message-ID: <20140509221552.GA32099@sara.home> 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 1399673765 22440 80.91.229.3 (9 May 2014 22:16:05 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 9 May 2014 22:16:05 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDELLREETMBRBG5HWWNQKGQED7H5JZQ@isocpp.org Sat May 10 00:15:58 2014 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ee0-f69.google.com ([74.125.83.69]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1Wit5A-0001XM-9a for gclcip-std-proposals@m.gmane.org; Sat, 10 May 2014 00:15:56 +0200 Original-Received: by mail-ee0-f69.google.com with SMTP id e51sf2841234eek.8 for ; Fri, 09 May 2014 15:15:56 -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:subject:message-id:mail-followup-to :mime-version:user-agent: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-disposition; bh=uASEYokwA6W920qJUjUPV/CR49BU/yJVcerlzuOXzSk=; b=hbEzEvmjg+06hr4VzlzY7HoL+zi5uOkMmnOzxFZD3xHjw31xFl6Q1yzR37vL4d0puu nS8R+e8/BHJt9mV6fq+ZWbXcjo997HwAdp0AsibpfUdA2mfcc1RDwO6NWKBr6YOwejT+ flRkXILj53wdkljcEZut/3Ak/dCUZ8CjEW9cuqVz+4iubQUpZg7q2h78OYLB/ibCeuIR 80LCDTXLjGfl/CXyEXfObouBW5cZiYDtPMCzrdtn8SERZF+kV9j0MdEIYJM2Z/ttN5Tq P+FOLKCdwVVWuT13dQ2bT2oRXcSXH3gPlKZ4xp/uRF6X7FmfHyM+K8Hr+7GQvSy0VW6c FlMA== X-Gm-Message-State: ALoCoQmywAyoRXLSjE7OqN366CgQZqTrtLhIZMZf6EwCSvILGKEE4QvEL3sWzuLKTTbvBf6U6WcV X-Received: by 10.180.206.33 with SMTP id ll1mr684235wic.5.1399673755988; Fri, 09 May 2014 15:15:55 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.152.19.74 with SMTP id c10ls58948lae.2.gmail; Fri, 09 May 2014 15:15:54 -0700 (PDT) X-Received: by 10.112.150.103 with SMTP id uh7mr12742354lbb.30.1399673754626; Fri, 09 May 2014 15:15:54 -0700 (PDT) Original-Received: from mail.lysator.liu.se (mail.lysator.liu.se. [2001:6b0:17:f0a0::3]) by mx.google.com with ESMTPS id ld9si1468138lab.44.2014.05.09.15.15.54 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Fri, 09 May 2014 15:15:54 -0700 (PDT) Received-SPF: pass (google.com: domain of magfr@lysator.liu.se designates 2001:6b0:17:f0a0::3 as permitted sender) client-ip=2001:6b0:17:f0a0::3; Original-Received: from mail.lysator.liu.se (localhost [127.0.0.1]) by mail.lysator.liu.se (Postfix) with ESMTP id 4270E4002A for ; Sat, 10 May 2014 00:15:54 +0200 (CEST) Original-Received: from sara.home (h-176-10-249-241.na.cust.bahnhof.se [176.10.249.241]) (using TLSv1 with cipher DHE-RSA-AES128-SHA (128/128 bits)) (No client certificate requested) by mail.lysator.liu.se (Postfix) with ESMTPSA id 2CBAB4001E for ; Sat, 10 May 2014 00:15:54 +0200 (CEST) Mail-Followup-To: std-proposals@isocpp.org User-Agent: Mutt/1.5.23 (2014-03-12) X-Virus-Scanned: ClamAV using ClamSMTP X-Original-Sender: magfr@lysator.liu.se X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of magfr@lysator.liu.se designates 2001:6b0:17:f0a0::3 as permitted sender) smtp.mail=magfr@lysator.liu.se 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: , Content-Disposition: inline Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:10593 Archived-At: Hello. One thing that have annoyed me for a while is that I can't declare that a name refers to a type unless I know if the name is a class-name or a typedef-name when all I want to say is that the name is something I can form a pointer or a reference to. I can say class foo; void f1(foo&); and I can also say using bar = int; void f2(bar&); but I lack the ability to say gaz; void f3(gaz&); where all that I tell the compiler is that gaz is a type, but don't have to say if it is a typedef-name or a class-name. Now, I do understand the reason for this since f2(bar&) should mangle like f2(int&) so this suggests some kind of "strong" typedef that introduces a new name for an existing type, and this is also an often requested feature. Would it be feasible to introduce a strong typedef in order to allow general forward declaration of types, or is this an utterly stupid idea? The strong typedef should introduce a new type and place it in the same namespace as class-names. So the proposal is something along the lines of // Declare two types, say nothing of what they contain strong typedef aType; strong typedef aClass; // Actually define the types strong typedef int aType; // possibly allow ommitting strong here? class aClass { }; /MF -- --- 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/. .