220 1480 article Path: news.gmane.org!not-for-mail From: Ville Voutilainen Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: making using declaration more precise Date: Mon, 7 Jan 2013 21:08:05 +0200 Lines: 56 Approved: news@gmane.org Message-ID: References: <738f626c-3b23-4c74-9eea-2c2246921a81@isocpp.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 1357585685 27677 80.91.229.3 (7 Jan 2013 19:08:05 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Mon, 7 Jan 2013 19:08:05 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBC5JHI7A7ALRBFV2VSDQKGQEB7HPBFI@isocpp.org Mon Jan 07 20:08:23 2013 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ie0-f198.google.com ([209.85.223.198]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1TsI3a-0006sC-J1 for gclcip-std-proposals@m.gmane.org; Mon, 07 Jan 2013 20:08:22 +0100 Original-Received: by mail-ie0-f198.google.com with SMTP id c10sf81268015ieb.5 for ; Mon, 07 Jan 2013 11:08:06 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=x-received:x-beenthere:x-received:x-received:received-spf :mime-version:in-reply-to:references:date:message-id:subject:from:to :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=jLSAsgcHS89uRbY2egtOUk7O0I5wdL3iW9gHrH4nKmw=; b=ZHxVheCoW9A8ZUB1BHMadaCYXV32TMdwEEXIkZW7iySrpsNdvqBYlIr5QtuBQsWBTA J4YtWC1E5y71HqBmp9i66kxp4+RlZEZ9Yu1r5mkYrfU1wrmQmw/WBcMmQLqIPBNkhRQn V0kC9dloJJA2Ildvfn558QTHMeVMtgazLN9+jPCg9b+IlXy3vJ1uu91Evlww+mPvvoNh IFmr790bzltH5kCNMUmazo8gwFsxj3pngxVi3lrxafkWr3foyGJ+qmqORyUljDd/vDRK BL0oxGaz0zW/fxhc/sBlei3xkly2IJ5UvxRhz7Gt5vWla5+nwNZzAC6+W9/xijicmQhF X-Received: by 10.182.154.42 with SMTP id vl10mr1475708obb.14.1357585686143; Mon, 07 Jan 2013 11:08:06 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.182.134.9 with SMTP id pg9ls1421764obb.44.gmail; Mon, 07 Jan 2013 11:08:05 -0800 (PST) X-Received: by 10.60.172.178 with SMTP id bd18mr35173507oec.133.1357585685699; Mon, 07 Jan 2013 11:08:05 -0800 (PST) X-Received: by 10.60.172.178 with SMTP id bd18mr35173505oec.133.1357585685666; Mon, 07 Jan 2013 11:08:05 -0800 (PST) Original-Received: from mail-ob0-f171.google.com (mail-ob0-f171.google.com [209.85.214.171]) by mx.google.com with ESMTPS id s1si56332247oeb.27.2013.01.07.11.08.05 (version=TLSv1/SSLv3 cipher=OTHER); Mon, 07 Jan 2013 11:08:05 -0800 (PST) Received-SPF: pass (google.com: domain of ville.voutilainen@gmail.com designates 209.85.214.171 as permitted sender) client-ip=209.85.214.171; Original-Received: by mail-ob0-f171.google.com with SMTP id dn14so17880928obc.30 for ; Mon, 07 Jan 2013 11:08:05 -0800 (PST) Original-Received: by 10.60.172.200 with SMTP id be8mr35389468oec.0.1357585685510; Mon, 07 Jan 2013 11:08:05 -0800 (PST) Original-Received: by 10.76.108.82 with HTTP; Mon, 7 Jan 2013 11:08:05 -0800 (PST) In-Reply-To: <738f626c-3b23-4c74-9eea-2c2246921a81@isocpp.org> X-Original-Sender: ville.voutilainen@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of ville.voutilainen@gmail.com designates 209.85.214.171 as permitted sender) smtp.mail=ville.voutilainen@gmail.com; dkim=pass header.i=@gmail.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:1480 Archived-At: On 5 January 2013 20:07, Arthur Tchaikovsky wrote: > I wonder if anyone feels the same as me about using declaration while > specifying members from base class? As things are now, it is very blunt and > not very precise tool, which could be quite easily tweaked. > What I mean is: > class A > { > public: > void f(); > void f(int); > }; > class B: public A > { > using A::f;//here we cannot make a choice on which one we would like to use > in our B class, which sometimes is ok... > }; > but in scenario: > class A > { > void f(int); > public: > void f(); > }; > class B :public A > { > using A::f;//will not compile even though the only fnc we want is A::f() > }; > What I would like to propose is following backwards compatible syntax: > class B :public A > { > using A::f;//here I'm specifying that I want use every fnc 'f' from A - just > like before, but this will not compile > using A::f();//here I explicitly specify which fnc I want to use > }; > The use case which is I believe compelling is the one that if function f > overloaded and one or more is declared private, this actively prohibits us > from the use of any other, non-private functions 'f' from the base class. > Looking forward to comments. The work-around would, I think, be class B :public A { void f(int x) {A::f(x);} }; Adding the new syntax doesn't seem to be compelling compared to the very low cost of specifying exactly the signatures you want and calling the base implementation of them. -- .