220 21981 article Path: news.gmane.org!not-for-mail From: "'Johannes Schaub' via ISO C++ Standard - Future Proposals" Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: Functions whose body is an expression Date: Sun, 25 Oct 2015 21:03:13 +0100 Lines: 48 Approved: news@gmane.org Message-ID: References: Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-Trace: ger.gmane.org 1445803401 25651 80.91.229.3 (25 Oct 2015 20:03:21 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sun, 25 Oct 2015 20:03:21 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCQPNCEZSQNBBAXLWSYQKGQETRAK7EI@isocpp.org Sun Oct 25 21:03:17 2015 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-lf0-f71.google.com ([209.85.215.71]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1ZqRVd-0000ay-6t for gclcip-std-proposals@m.gmane.org; Sun, 25 Oct 2015 21:03:17 +0100 Original-Received: by lfaz124 with SMTP id z124sf70004083lfa.0 for ; Sun, 25 Oct 2015 13:03:16 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:date :message-id:subject:from:to:content-type:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=UarHFBmMvYFWETPRJGnfagkBQBy7fqVb2E1WVRPeGZU=; b=X2lNxCICMQ4FiZYnolo8DCT4JljToslGJfI4is8njbSzxmMq7GgEPt3FI8LEcgSphj OnnpNkGxvd7ePklOBrnx7TKkVbUNDXHW+dl9woLjuHanPb+hA9dzRaoKC4HGak0pecbg RAaMuIyOxlwjp+zklNjisYXV5aE2uEmEIbNjcOEqUdj1fVo7Hfc3wZdG1chxA1Ubjdoi 1r14mBwUaSgBfr0RsFrqbMGZSEUA1doKEB06Ki1+usxV+vUaA1K7zmLwcD1d3MDPX3C0 8Ei51Ak7is6BdtxQ22e91A7lgefxi6VsYMm6QlNPFShnti+gd2GGYJA/h3+SzxioYjOV ui4g== X-Gm-Message-State: ALoCoQmlQU59SXURmiPbchYifhK1+4bznS68euJHrLgnfxVwFW1C/aRxA4QK8Xnte6joqsFhbpIR X-Received: by 10.28.211.201 with SMTP id k192mr340842wmg.3.1445803396679; Sun, 25 Oct 2015 13:03:16 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.25.25.67 with SMTP id 64ls600693lfz.41.gmail; Sun, 25 Oct 2015 13:03:14 -0700 (PDT) X-Received: by 10.112.151.37 with SMTP id un5mr1224107lbb.53.1445803394283; Sun, 25 Oct 2015 13:03:14 -0700 (PDT) Original-Received: from mail-lf0-x233.google.com (mail-lf0-x233.google.com. [2a00:1450:4010:c07::233]) by mx.google.com with ESMTPS id mt6si18760549lbb.32.2015.10.25.13.03.14 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 25 Oct 2015 13:03:14 -0700 (PDT) Received-SPF: pass (google.com: domain of schaub.johannes@googlemail.com designates 2a00:1450:4010:c07::233 as permitted sender) client-ip=2a00:1450:4010:c07::233; Original-Received: by lffz202 with SMTP id z202so127963999lff.3 for ; Sun, 25 Oct 2015 13:03:13 -0700 (PDT) X-Received: by 10.25.22.38 with SMTP id m38mr10075869lfi.10.1445803393523; Sun, 25 Oct 2015 13:03:13 -0700 (PDT) Original-Received: by 10.112.74.132 with HTTP; Sun, 25 Oct 2015 13:03:13 -0700 (PDT) In-Reply-To: X-Original-Sender: schaub.johannes@googlemail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of schaub.johannes@googlemail.com designates 2a00:1450:4010:c07::233 as permitted sender) smtp.mailfrom=schaub.johannes@googlemail.com; dkim=pass header.i=@googlemail.com; dmarc=pass (p=QUARANTINE dis=NONE) header.from=googlemail.com Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Spam-Checked-In-Group: std-proposals@isocpp.org X-Google-Group-Id: 399137483710 List-Post: , List-Help: , List-Archive: List-Subscribe: , List-Unsubscribe: , X-Original-From: Johannes Schaub Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:21981 Archived-At: 2015-10-25 18:32 GMT+01:00 Nicol Bolas : > > > On Sunday, October 25, 2015 at 10:42:50 AM UTC-4, Johannes Schaub wrote: >> >> Hello all, my proposal is to allow an initializer (expression) as function >> body >> >> int abs(int x) = x > 0 ? x : -x; >> >> Or, (with support of SFINAE and overloadability!) >> >> template auto size(T &&t) = t.sizte(); >> template auto size(T &&t) = t.count(); >> template auto size(T &&t) = t.length(); > > > First, that's not overloading, since SFINAE makes the other declarations > disappear. And if it doesn't, you get a straight-up compilation error. That > is, you can't pass a `T` that has both `size` and `count`. > Well, this is overloading. But not overload resolution (to be hairsplitting, it's like 5% overload resolution because a candidate set is still formed..). > Second, this would be better done with concepts, since the concept would > make it much more obvious what's going on: > > auto size(HasSize &&t) {return t.size();} > auto size(HasCount &&t) {return t.count();} > auto size(HasLength &&t) {return t.length();} > > Also, such concepts would be a lot more specific. Rather than checking a > single member function or something, they'd be based on things like > `Container` or whatever. > This is a good point. Sufficient to make me forget about this. Thanks! -- --- You received this message because you are subscribed to the Google Groups "ISO C++ Standard - Future Proposals" group. 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