220 8728 article Path: news.gmane.org!not-for-mail From: Jeffrey Yasskin Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: string_view::is_null() Date: Sun, 19 Jan 2014 22:12:55 -0800 Lines: 29 Approved: news@gmane.org Message-ID: References: <104254A6-C69A-4571-8455-89D7E466D493@gmail.com> <6a95bf9c-55c9-4ae2-966f-d1b1f4df6a37@isocpp.org> <52D9E336.1060801@knejp.de> <1B534FD7-B385-4A7E-A718-3C73F0AB61DC@gmail.com> <11f13f8f-1270-427c-8942-94027a181ff4@isocpp.org> <20140119174431.GA16875@faust.lysator.liu.se> <20140119192238.GA19497@faust.lysator.liu.se> <60842af6-5ec4-4364-b2d5-a0be9d578bd6@isocpp.org> <6c82c4ae-c144-443a-81b2-ea1a6b645601@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 1390198390 18036 80.91.229.3 (20 Jan 2014 06:13:10 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Mon, 20 Jan 2014 06:13:10 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDDM34EO6QDRB6746KLAKGQEDAIRJKQ@isocpp.org Mon Jan 20 07:13:18 2014 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-pb0-f71.google.com ([209.85.160.71]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1W586n-0005pt-7L for gclcip-std-proposals@m.gmane.org; Mon, 20 Jan 2014 07:13:17 +0100 Original-Received: by mail-pb0-f71.google.com with SMTP id jt11sf11691579pbb.2 for ; Sun, 19 Jan 2014 22:13:16 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject: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; bh=NukRf+QA4jlZj8O1R5/4oQabVvrSwuKOeGOD0MQEcO8=; b=l9NZAC71ZR0XymGPKsPJolp0VJbYdpRei876p+S135WJCgl7kGxc9KdESST3qLHCr/ OMyaqey2DcwcL8t53iYiLhkT0ZBp9FG4hJ4qALxK/h+IaTnZSDN8sQNrt7ABv2mbYg7T H+n2PFtK2c5//VNXDIcYtWcyI53CBvK3Yze7GeJFudpl5apf/GV6x77Gbn1r7R2eiyXD CAYrHRU03hjpIzXo+52cv9Ek4x3OVwWKH/wPFCHgIzBpU6CdFjUk/GieujHRNYp6rzRZ XSTS0F+BCi7TjZNtv8uXybz2hiq2KMYjflVGH3x6LzUp34t7fTX8goTvxV/1iltonxk4 V9yg== 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:from:date :message-id:subject: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; bh=NukRf+QA4jlZj8O1R5/4oQabVvrSwuKOeGOD0MQEcO8=; b=d/KUiglt5EpVjcpucGyM5LBOQdJ3aJJwWJgBOQHVX4yIgLpOUKtj+PrlrVrVzaJbbB f3sJYvs3oKTkEBsZCn2WjMiNlM0744J0V3Nhpdrvl/HeHBGtPiJvy8FVMjmIpAFeg7hT m8LDiwp20n7VJYZu0dylUTyUMkiuXBoAPtHFWh/pYbwlZiffPufNUSfJ3sYutTsapjTt a+tA35UIvf3hvRu9+uIN6Wx67YmPjJubjgYe0tOAqP2bUixffCbpVMNcONL+EHSpdgQo D6aePjCpsMjbH2AaxKQue6qjRbT8pImr0tqDxeQqZBUCsVBbQRAj7a/AgqLLoFCzWMNd PHIw== X-Gm-Message-State: ALoCoQmqSuoRUGDyngcikEMwBaGW4YVnBQk28ip8sIWINa8D0xwlbHLTRSdES+Tem8IPuqE2qVRh X-Received: by 10.66.6.1 with SMTP id w1mr5877082paw.6.1390198396071; Sun, 19 Jan 2014 22:13:16 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.140.32.228 with SMTP id h91ls935003qgh.14.gmail; Sun, 19 Jan 2014 22:13:15 -0800 (PST) X-Received: by 10.224.51.196 with SMTP id e4mr25052171qag.16.1390198395361; Sun, 19 Jan 2014 22:13:15 -0800 (PST) Original-Received: from mail-qe0-x22b.google.com (mail-qe0-x22b.google.com [2607:f8b0:400d:c02::22b]) by mx.google.com with ESMTPS id q10si6093qaj.14.2014.01.19.22.13.15 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Sun, 19 Jan 2014 22:13:15 -0800 (PST) Received-SPF: pass (google.com: domain of jyasskin@google.com designates 2607:f8b0:400d:c02::22b as permitted sender) client-ip=2607:f8b0:400d:c02::22b; Original-Received: by mail-qe0-f43.google.com with SMTP id nc12so6047727qeb.16 for ; Sun, 19 Jan 2014 22:13:15 -0800 (PST) X-Received: by 10.224.97.7 with SMTP id j7mr25227035qan.81.1390198395173; Sun, 19 Jan 2014 22:13:15 -0800 (PST) Original-Received: by 10.229.226.196 with HTTP; Sun, 19 Jan 2014 22:12:55 -0800 (PST) In-Reply-To: X-Original-Sender: jyasskin@google.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of jyasskin@google.com designates 2607:f8b0:400d:c02::22b as permitted sender) smtp.mail=jyasskin@google.com; dkim=pass header.i=@google.com; dmarc=pass (p=REJECT dis=NONE) header.from=google.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:8728 Archived-At: On Sun, Jan 19, 2014 at 10:01 PM, Nevin Liber wrote: > On 19 January 2014 22:07, Paul Tessier wrote: >> >> Why would ( nullptr, 3 ) be considered an empty view? > > > It would be undefined behavior. > > My personal preference for all this is that string_view(nullptr, 0) be > allowed, and it is a Quality of Implementation issue whether or not > sv.data() can ever return a nullptr; i.e., it would be allowed to return any > legal pointer it wants for an empty string_view. That's interesting. It's easier to both specify and implement to just say that string_view(x, y).data()==x and string_view(x, y).size()==y, assuming [x, x+y) is a valid range. Why would you special-case data() to return arbitrary things when y==0? Thanks, Jeffrey (who's adding the data()==nullptr option to the paper as we speak) -- --- 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/. .