220 28421 article Path: news.gmane.org!.POSTED!not-for-mail From: =?UTF-8?Q?Daniel_Kr=C3=BCgler?= Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Marking more std::string_view members noexcept Date: Tue, 27 Sep 2016 19:47:00 +0200 Lines: 40 Approved: news@gmane.org Message-ID: References: <3d03cd7d-2177-98fd-408d-f74b1f6a8552@gmail.com> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-Trace: blaine.gmane.org 1474998433 7645 195.159.176.226 (27 Sep 2016 17:47:13 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Tue, 27 Sep 2016 17:47:13 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCT7RVFA4QORBFPBVK7QKGQEP4ROXEQ@isocpp.org Tue Sep 27 19:47:08 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-lf0-f72.google.com ([209.85.215.72]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1bowT6-0000NT-Cx for gclcip-std-proposals@m.gmane.org; Tue, 27 Sep 2016 19:47:00 +0200 Original-Received: by mail-lf0-f72.google.com with SMTP id b71sf22618939lfg.2 for ; Tue, 27 Sep 2016 10:47:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; 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:x-spam-checked-in-group:list-post :list-help:list-archive:list-subscribe:list-unsubscribe; bh=/kOVh0icwRBzoT54mBvpPjnl8pO1ruk+2CXLM7NytaU=; b=G7vcvTcmIQaHJGccMr2999prafAjIacQNbwJx9HPl7gNR0LJJUdWsIaK1H4kPQCyqU 9jLtSAgBBblOQ7/ys/jTVcy2bh1kXL6PkJu7/RD6MnNrBBNJf5snOjife0EWZk2oySxk johbylDaqnXJM0xYJUqDR48nQWp5mbXq7p/nn8CVML0tiRPyYLIiVtpTQHJ9YeJUH/OM j9mi/Apx2n3B0mWldHgIeklVTLIVliJcILUeKvHQFfpvZ2922TPByjyaueJx/DzREFsh VFFVTRho9UmnKpViSf3oOhZPqSX1swOSpHacM36DGYo/xJ8NDjMW8SBVA6Ohl8Za4T8s 3HPg== 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:x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=/kOVh0icwRBzoT54mBvpPjnl8pO1ruk+2CXLM7NytaU=; b=TKQ7yzixoHRNZYg3e9/bKOG6uFC0c8qXpNNsRlDTcnoIP47eTEaxB0C8Oyw61jR7ba jt0ekRCCrCpuEyEGlz79XTgUTAReCFoH96ofZQ2w/DsDq8jtV4ujFXX623v34jk+5x7s xElgyC9K5zjAY7v/xjaY6dTTcxqzsnLeMKVzzTCzMSVWFn0XhBkwiEAAgfWedR0sL1WL 33IUZYj01W6ZvV9MvnaQjerHliq/QG5GiigBpWfA2q6r4fCzM6MzJbhOhAMsJZrKd7wJ bmG1Fp4FNz1NezEi4CR3nm5IkDqalH+FT3z0mLuWLvfqkzt2hKFH3D66qa1gVIOtBLWh zNFQ== X-Gm-Message-State: AE9vXwNVBHy2mN0/EVSCBVaiZIzDtz4CtufGKw4xBMTB/WAKKQfR2cqewt2NoBfCdjc1Hw== X-Received: by 10.25.204.21 with SMTP id c21mr1502423lfg.19.1474998422363; Tue, 27 Sep 2016 10:47:02 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.28.17.7 with SMTP id 7ls2048280wmr.0.canary; Tue, 27 Sep 2016 10:47:01 -0700 (PDT) X-Received: by 10.28.181.145 with SMTP id e139mr4093839wmf.114.1474998421216; Tue, 27 Sep 2016 10:47:01 -0700 (PDT) Original-Received: from mail-wm0-x22d.google.com (mail-wm0-x22d.google.com. [2a00:1450:400c:c09::22d]) by mx.google.com with ESMTPS id 8si14855257wmo.24.2016.09.27.10.47.01 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 27 Sep 2016 10:47:01 -0700 (PDT) Received-SPF: pass (google.com: domain of daniel.kruegler@gmail.com designates 2a00:1450:400c:c09::22d as permitted sender) client-ip=2a00:1450:400c:c09::22d; Original-Received: by mail-wm0-x22d.google.com with SMTP id w84so189363809wmg.1 for ; Tue, 27 Sep 2016 10:47:01 -0700 (PDT) X-Received: by 10.194.81.106 with SMTP id z10mr23344727wjx.140.1474998420601; Tue, 27 Sep 2016 10:47:00 -0700 (PDT) Original-Received: by 10.28.167.12 with HTTP; Tue, 27 Sep 2016 10:47:00 -0700 (PDT) In-Reply-To: <3d03cd7d-2177-98fd-408d-f74b1f6a8552@gmail.com> X-Original-Sender: daniel.kruegler@gmail.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com; spf=pass (google.com: domain of daniel.kruegler@gmail.com designates 2a00:1450:400c:c09::22d as permitted sender) smtp.mailfrom=daniel.kruegler@gmail.com; dmarc=pass (p=NONE dis=NONE) header.from=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:28421 Archived-At: 2016-09-27 14:21 GMT+02:00 Andrey Semashev : > Hi, > > I'm looking at string_view interface definition in N4606 and wondering why > so many members are not marked noexcept? For example, these constructors: > > constexpr basic_string_view(const charT* str); > constexpr basic_string_view(const charT* str, size_type len); > > Assuming that the input string is not a constant expression, the first > constructor would call an equivalent of strlen(str), which in 99% is a > no-throw operation. Why not mark it > "noexcept(noexcept(traits::length(str))"? The second constructor does not > even need that and could be simply noexcept. > > I'm most interested in constructors, but other members like operator[], > front(), back(), substr(), compare() also don't seem to need to ever throw, > yet they are not marked noexcept. > > Is there a reason for these omissions? This is so, because these functions have a narrow contract. The current guideline for LWG was described by this proposal: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3279.pdf > Also, why there is no obvious constructor from basic_string? Which one in particular is in your mind? Thanks, - Daniel -- 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. To view this discussion on the web visit https://groups.google.com/a/isocpp.org/d/msgid/std-proposals/CAGNvRgBSk47UXuzh_jm_Yr2pBCM5NYSZ8kqVjwLyWsm-4r6ozw%40mail.gmail.com. .