220 17295 <1689946.eYtMPifRN2@tjmaciei-mobl4> article Path: news.gmane.org!not-for-mail From: Thiago Macieira Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: noexcept(auto) Date: Tue, 07 Apr 2015 08:01:16 -0700 Lines: 43 Approved: news@gmane.org Message-ID: <1689946.eYtMPifRN2@tjmaciei-mobl4> References: <1657285.u9ziYB6mWs@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 Content-Transfer-Encoding: quoted-printable X-Trace: ger.gmane.org 1428418893 5945 80.91.229.3 (7 Apr 2015 15:01:33 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 7 Apr 2015 15:01:33 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCB4TK757YBRBRPCR6UQKGQE2GSZSBI@isocpp.org Tue Apr 07 17:01:26 2015 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-la0-f71.google.com ([209.85.215.71]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1YfV0I-0005LC-IA for gclcip-std-proposals@m.gmane.org; Tue, 07 Apr 2015 17:01:26 +0200 Original-Received: by labgx2 with SMTP id gx2sf13698387lab.1 for ; Tue, 07 Apr 2015 08:01:26 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:subject:date:message-id:user-agent :in-reply-to:references:mime-version:content-transfer-encoding :content-type:x-original-sender:x-original-authentication-results :reply-to:precedence:mailing-list:list-id:list-post:list-help :list-archive:list-subscribe:list-unsubscribe; bh=Or7i+qvegQWppapQWs/jUzTizWGkdQbUQpnNbimjwjU=; b=X88bAkTXA4i0B+3gitaqlp8YVH102UxDRgoByi7VfZbw4Y7n2ie+Mdg79724z1WkoF 24mwxpp+a7/1CclLu9ISk74nykcqESj/tfIC2JMHv+xk9xxwe2IbFjxOw2P2Q7LdUKVR eni4w2MZNBq88VnigIRThRi6fo+Td7zOq8NfG0eBHtnLg7TWkCp/d7/aXLnsw4u3J/UY qoGF/1thOe+P56HdP1oJbK3lY4pyRaIIwTW+PNBs4fSa8EM2Ljp0Emx8GTSwfznXSTxt /TlISWqoPohYNCsflpWitwtQ6jyFqOrmvNEHp1SYa2F4YlWp0wgTnZgE1zW8nr+7f2ss bV5 X-Gm-Message-State: ALoCoQlgGjeAn9mrY6vaBmjswtwXhtWNx/4MNNgo2G2hGYAyZOzy5esnkX1jhxhqq2kjHSkx5XrE X-Received: by 10.194.11.70 with SMTP id o6mr4218434wjb.6.1428418885945; Tue, 07 Apr 2015 08:01:25 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.180.100.133 with SMTP id ey5ls53492wib.32.canary; Tue, 07 Apr 2015 08:01:24 -0700 (PDT) X-Received: by 10.194.109.9 with SMTP id ho9mr40178860wjb.29.1428418884943; Tue, 07 Apr 2015 08:01:24 -0700 (PDT) Original-Received: from gondolin.macieira.info (gondolin.macieira.info. [78.47.120.188]) by mx.google.com with ESMTP id db1si13281394wib.84.2015.04.07.08.01.23 for ; Tue, 07 Apr 2015 08:01:23 -0700 (PDT) Received-SPF: pass (google.com: domain of thiago@macieira.org designates 78.47.120.188 as permitted sender) client-ip=78.47.120.188; Original-Received: from tjmaciei-mobl4.localnet (unknown [IPv6:2601:7:1c80:b36:30eb:baa0:5206:8ce4]) by gondolin.macieira.info (Postfix) with ESMTPSA id 6D94111BAFB for ; Tue, 7 Apr 2015 08:01:23 -0700 (PDT) User-Agent: KMail/4.14.6 (Linux/3.19.3-1-desktop; KDE/4.14.6; x86_64; ; ) In-Reply-To: X-Original-Sender: thiago@macieira.org X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of thiago@macieira.org designates 78.47.120.188 as permitted sender) smtp.mail=thiago@macieira.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:17295 Archived-At: On Tuesday 07 April 2015 11:41:35 David Rodr=C3=ADguez Ibeas wrote: > void reset_element(std::vector & v, size_t index) { > if (index < v.size()) v.at(index) =3D 0; > } >=20 > The compiler sees the call to 'v.at' and would assume the function to be > 'noexcept(false)', but it is really 'noexcept(true)', it is guaranteed no= t > to throw. While the example is crappy, it represents a whole family of > functions that can call on 'noexcept(false)' functions but for which the > code ensures that no exception will be really thrown. >=20 > I am in favor of using 'auto' as a short hand for "deduce it for me" (or = at > the very least not against it), but I don't really think that the compile= r > should be injecting noexcept declarations for the programmer implictly. > Those "magic 14 characters" are really the user requesting that the > compiler to do it. In this example, without the magic, the code is noexcept(false). So if the= =20 compiler deduces as false again, there's no loss. If you need to tell the compiler otherwise, you still can. --=20 Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org Software Architect - Intel Open Source Technology Center PGP/GPG: 0x6EF45358; fingerprint: E067 918B B660 DBD1 105C 966C 33F5 F005 6EF4 5358 --=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/. .