220 16801 <54F930C8.30609@coverity.com> article Path: news.gmane.org!not-for-mail From: Tom Honermann Newsgroups: gmane.comp.lang.c++.isocpp.proposals,gmane.comp.lang.c++.isocpp.general Subject: Re: Re: [c++std-core-27216] Re: An implementation of enhanced auto deduction and abbreviated template syntax using Clang Date: Thu, 5 Mar 2015 23:44:56 -0500 Lines: 55 Approved: news@gmane.org Message-ID: <54F930C8.30609@coverity.com> References: <54F91983.2020808@stroustrup.com> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed X-Trace: ger.gmane.org 1425617118 831 80.91.229.3 (6 Mar 2015 04:45:18 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 6 Mar 2015 04:45:18 +0000 (UTC) Cc: "std-discussion@isocpp.org" , "faisalv@gmail.com" To: , Original-X-From: std-proposals+bncBDBNXSHG6UDBBUXB4STQKGQELVXDX3I@isocpp.org Fri Mar 06 05:45:10 2015 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-vc0-f198.google.com ([209.85.220.198]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1YTk8K-0005xo-D5 for gclcip-std-proposals@m.gmane.org; Fri, 06 Mar 2015 05:45:08 +0100 Original-Received: by mail-vc0-f198.google.com with SMTP id hq11sf19399265vcb.1 for ; Thu, 05 Mar 2015 20:45:07 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:message-id:date:from:user-agent:mime-version:to :cc:subject:references:in-reply-to:content-type:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:list-post:list-help:list-archive:list-subscribe :list-unsubscribe; bh=T+JVZcUdvziRQdxuqSuxFHLAQ1q0ph4AbEyvLgLxDTA=; b=myQhJVQAxUcFFCJ6llzTudJi7MNMZOvHshpYkEwdaU8ciPqNQwFO3qGfl6Y7Jzhb9f b9EoQlQ3pJb7wUemCM4EgSCIuXQTQbRv8TS1Fv5tr0fgku6bPAvR9Sv3OSUX1R5NO63F +4SIi0i2fV6GscS88W8/jPgdCM5XDUQ96zgF9ZtHMvBm7mouITp8vVd2y0qkdxOJXnA5 jMGRwg7dF28w+Hl+/Tc1TiYS7ukhar/n4QueLRYru5/8Va/bEeh5/i85GCXVBBmIHo5v O9YaoxtnsQcHn0QukYLHeuwlwy1softn0VCZnkj/Tu3w6fpjWJcq7gb8cg8fxBxd94js VkFQ== X-Gm-Message-State: ALoCoQmtpPddKqijvRN+oiFfiyH0RdUyBn+1Vm5E6f07c0x1FajMauxh1j5NFqzORbvtxxz28a62 X-Received: by 10.236.223.166 with SMTP id v36mr12749700yhp.45.1425617107395; Thu, 05 Mar 2015 20:45:07 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.50.65.33 with SMTP id u1ls54208igs.30.canary; Thu, 05 Mar 2015 20:45:05 -0800 (PST) X-Received: by 10.70.98.197 with SMTP id ek5mr22348834pdb.104.1425617105881; Thu, 05 Mar 2015 20:45:05 -0800 (PST) Original-Received: from na01-by2-obe.outbound.protection.outlook.com (mail-by2on0133.outbound.protection.outlook.com. [207.46.100.133]) by mx.google.com with ESMTPS id hc6si12770167pbc.21.2015.03.05.20.45.05 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Thu, 05 Mar 2015 20:45:05 -0800 (PST) Received-SPF: pass (google.com: domain of thonermann@coverity.com designates 207.46.100.133 as permitted sender) client-ip=207.46.100.133; Original-Received: from [192.168.1.13] (173.53.22.182) by BY2PR05MB711.namprd05.prod.outlook.com (10.141.222.149) with Microsoft SMTP Server (TLS) id 15.1.106.15; Fri, 6 Mar 2015 04:45:03 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.4.0 In-Reply-To: <54F91983.2020808@stroustrup.com> X-Originating-IP: [173.53.22.182] X-ClientProxiedBy: BL2PR01CA0049.prod.exchangelabs.com (10.141.66.49) To BY2PR05MB711.namprd05.prod.outlook.com (10.141.222.149) X-Microsoft-Antispam: UriScan:;BCL:0;PCL:0;RULEID:;SRVR:BY2PR05MB711; X-Forefront-Antispam-Report: BMV:1;SFV:NSPM;SFS:(10019020)(6049001)(6009001)(24454002)(377454003)(479174004)(36756003)(50466002)(66066001)(47776003)(65806001)(42186005)(2950100001)(122386002)(40100003)(50986999)(77156002)(62966003)(23676002)(83506001)(561944003)(76176999)(46102003)(230783001)(65816999)(92566002)(54356999)(87976001)(33656002)(117156001)(77096005)(86362001);DIR:OUT;SFP:1102;SCL:1;SRVR:BY2PR05MB711;H:[192.168.1.13];FPR:;SPF:None;MLV:sfv;LANG:en; X-Microsoft-Antispam-PRVS: X-Exchange-Antispam-Report-Test: UriScan:; X-Exchange-Antispam-Report-CFA-Test: BCL:0;PCL:0;RULEID:(601004)(5002007)(5005006);SRVR:BY2PR05MB711;BCL:0;PCL:0;RULEID:;SRVR:BY2PR05MB711; X-Forefront-PRVS: 05079D8470 X-OriginatorOrg: coverity.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 06 Mar 2015 04:45:03.9929 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-Transport-CrossTenantHeadersStamped: BY2PR05MB711 X-Original-Sender: thonermann@coverity.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of thonermann@coverity.com designates 207.46.100.133 as permitted sender) smtp.mail=thonermann@coverity.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:16801 gmane.comp.lang.c++.isocpp.general:5006 Archived-At: On 03/05/2015 10:05 PM, Bjarne Stroustrup wrote: > (1) people always ask for heavier syntax from new features > (2) people learn > (3) people always complain that the syntax they insisted on is too heavy > handed I think there is truth in that. However, I think some other languages have demonstrated the opposite problem. For example, Perl has been criticized (fairly or not, I'm not judging) for allowing overly terse syntax and sometimes termed a "write-only language" due to a common perception that maintaining Perl code is difficult as a result. I'm not trying to defend that argument here, just pointing out that the perception exists. I think the abbreviated syntax goes too far as currently proposed. It is hard to imagine a more terse syntax that doesn't require dropping type placeholders completely. I stated elsewhere in this thread that I don't mind the current, rather heavy, template syntax, but that doesn't mean that I wouldn't appreciate a lighter syntax. If there were not significant semantic differences between template function definitions and non-template function definitions, then I would love the abbreviated syntax. The fact is though, that there are significant semantic differences and some of them are quite subtle. I don't feel concerned about point of usage of functions declared with the abbreviated syntax. The behavioral differences aren't that great in that case. My concern is with maintenance of functions declared with this syntax and maintainers not realizing that a template is being modified. Richard supplied an excellent list a few emails back illustrating some of the problems one can encounter switching a simple traditionally declared template function to an abbreviated one. I think his insights should not be overlooked here (or, anywhere else, really). I would be quite happy with the smallest addition to the proposal that makes it clear that "this is a template function" and that doesn't rely on my ability to scan for 'auto' or identify the name of a concept in the parameter list. We have this for lambdas: auto l = [](auto x) { return x; } If we could do (something like) these for generic functions, I would be thrilled: auto <>f(auto x) { return x; } auto <>f(Iterator i) { return i; } Tom. -- --- 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/. .