220 9274 article Path: news.gmane.org!not-for-mail From: Matthew Woehlke Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: add "implicit" keyword? Date: Tue, 11 Feb 2014 11:59:21 -0500 Lines: 67 Approved: news@gmane.org Message-ID: References: <1576598.9cS7S6zRmC@tjmaciei-mobl4> 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 Content-Transfer-Encoding: quoted-printable X-Trace: ger.gmane.org 1392137971 7221 80.91.229.3 (11 Feb 2014 16:59:31 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 11 Feb 2014 16:59:31 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCO5FYHBU4ERB55N5GLQKGQELTPTNRA@isocpp.org Tue Feb 11 17:59:39 2014 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-wi0-f198.google.com ([209.85.212.198]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1WDGgK-0007Kd-9l for gclcip-std-proposals@m.gmane.org; Tue, 11 Feb 2014 17:59:36 +0100 Original-Received: by mail-wi0-f198.google.com with SMTP id cc10sf10227260wib.1 for ; Tue, 11 Feb 2014 08:59:36 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:to:from:subject:date:lines:message-id:references :mime-version:user-agent:in-reply-to: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=XI8aUjtHFbULjXabZxG7nRTzomYSXdZpm7d6TrsYdxM=; b=YzsMivZYklLAEvqUWz0mIxdVcXSFpu21MaiqidsT9qov5qqR3AYiNYhKmInFZ5mSut bcYOpFt2aQa6rFEdemy38+HxTFuWSQppK/L/mPQmDEh28anyhnzPLdHaKppegAbWw6S+ OoFqPjFNZ3iZnQ1j3TkGiXWpiB76Tt5wxdT1gvJywaLv8WrnyjLj2WwyJH7NxNLQGXH9 SY8d6yKOoVGVI7qvM6vD8rvJEi5ug8gFHRPPNiDaKuJc9Yl6xmmzAnjY/RkufgnfbeNF My53wPdMzYXSBdRfsK8SIObBzq1QvSwb6WxC8iOsY/UF6nSx2qGjyTaI97gwf9tZ0/KA X-Gm-Message-State: ALoCoQkQcUDqG8Oi8U6FgY2Xlic7FdYq+lN8Hd+qBNlUmevTTFifm4StvS8/x8a6MzyHYMQnie6V X-Received: by 10.112.29.114 with SMTP id j18mr251505lbh.23.1392137975826; Tue, 11 Feb 2014 08:59:35 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.152.9.199 with SMTP id c7ls357347lab.104.gmail; Tue, 11 Feb 2014 08:59:35 -0800 (PST) X-Received: by 10.112.205.5 with SMTP id lc5mr2445647lbc.40.1392137974980; Tue, 11 Feb 2014 08:59:34 -0800 (PST) Original-Received: from plane.gmane.org (plane.gmane.org. [80.91.229.3]) by mx.google.com with ESMTPS id y6si10347163lal.166.2014.02.11.08.59.34 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Tue, 11 Feb 2014 08:59:34 -0800 (PST) Received-SPF: pass (google.com: domain of gclcip-std-proposals@m.gmane.org designates 80.91.229.3 as permitted sender) client-ip=80.91.229.3; Original-Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1WDGgI-0007Ib-8r for std-proposals@isocpp.org; Tue, 11 Feb 2014 17:59:34 +0100 Original-Received: from tripoint.kitware.com ([66.194.253.20]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Tue, 11 Feb 2014 17:59:34 +0100 Original-Received: from mw_triad by tripoint.kitware.com with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Tue, 11 Feb 2014 17:59:34 +0100 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 49 Original-X-Complaints-To: usenet@ger.gmane.org X-Gmane-NNTP-Posting-Host: tripoint.kitware.com User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 In-Reply-To: <1576598.9cS7S6zRmC@tjmaciei-mobl4> X-Original-Sender: mw_triad@users.sourceforge.net X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of gclcip-std-proposals@m.gmane.org designates 80.91.229.3 as permitted sender) smtp.mail=gclcip-std-proposals@m.gmane.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:9274 Archived-At: On 2014-02-11 02:34, Thiago Macieira wrote: > Em ter 11 fev 2014, =C3=A0s 14:19:09, David Krauss escreveu: >> This is stylistically fine, completely portable, and easy to understand >> (given a comment). It doesn't break anything except use of implicit as a= n >> identifier, which the proposal does too. (Users would be well advised to= do >> this only after all third-party library #includes.) > > The proposal was for a context-dependent keyword. It would not break uses= of > "implicit" as an identifier elsewhere. > > Question: if it's context-dependent, would it be allowed only to the righ= t of > the parameter list? No. In fact (like 'explicit') it would not be allowed to the right; see=20 original mail for the parse rules. Examples: class Foo { implicit Foo(int); // okay explicit Foo(float); // okay Foo(short) implicit; // error, expected ';' after declaration Foo(double) explicit; // error, expected ';' after declaration implicit operator int(); // okay implicit operator+(int); // error, 'implicit' does not name a type }; int implicit; // okay, declared an int variable named "implicit" using implicit =3D int; class Bar { implicit operator+(int); // okay (but ugly), return type is int int operator-(implicit); // okay (but ugly), takes an int }; > It might not be, since only constructors and cast operators can be implic= it > and those cannot have return types, so the presence of the keyword there = would > not be ambiguous. It might just be ugly: > > struct implicit { > implicit implicit(int); > explicit implicit(long); > }; Eew. Yes, that's ugly :-). But would be allowed. --=20 Matthew --=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/. .