220 31456 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: Allow access to std::array's underlying C-array Date: Mon, 6 Mar 2017 19:33:16 +0100 Lines: 35 Approved: news@gmane.org Message-ID: References: <52147c7c-ff38-4eaf-9f73-7f40628e9d58@isocpp.org> 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 1488825214 3199 195.159.176.226 (6 Mar 2017 18:33:34 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Mon, 6 Mar 2017 18:33:34 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCT7RVFA4QORB3OW63CQKGQESBYQCVI@isocpp.org Mon Mar 06 19:33:28 2017 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 1ckxRi-00088s-1A for gclcip-std-proposals@m.gmane.org; Mon, 06 Mar 2017 19:33:22 +0100 Original-Received: by mail-lf0-f72.google.com with SMTP id v2sf83955650lfi.2 for ; Mon, 06 Mar 2017 10:33:28 -0800 (PST) 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=hcMdcnfNYdZlUb4ohi8pqnFibwqPvfwmZdpXSpU+d/M=; b=0SmrIVClt0FFQ8zCJ1ltTmEyeKGbP81rWUC0Uz+wp2uPUWpKgxrf3NyEoEgBYOvqYr p5t1rVIMxCB1WFwxE8Yx0+0Yw8m72aU+RHlE+2YsxL9pWGNHg15vUdkVdAx5g05RXeqJ qMQ0tJIm+BSBUnmbPvbXuNCu0htimT8O775vOAX4z7HLX7eqls3bw99103kNXrJEe+VO hjiLGwqAGed0myPpZpvBAK6HCvRecJd9ygAdwD/JKTJUiYOGRvU5v73z0jmBGyDSzvro MTNJsHuVxhaBxdBBmMRg249R7v1rHEXDZmsDJiQtt/4kmZN5d3A3M7ZihRq2fjBpMjCD DKlA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; 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=hcMdcnfNYdZlUb4ohi8pqnFibwqPvfwmZdpXSpU+d/M=; b=MV3fO50T/eky8Qxj1NYh+XIJsWvKL+j7SphD8W/ymWOF3tUdmf0i6ug8RUkihyToGZ +k0dZvKvCv2b3pgCRkX4s3fUgXjUTv/HREDOv+lQHbIguyFDWG2TJpggObSegiCKObkc FUzN7NiIo6ZZVrJklkHOyF88ZFtpeIwzXu7trKeoAsBws2pS1UjrNhUJD6flXv9YVlf7 0Jyu8RaPJXr0iuP6ZlxdiEu9tkDar2PAEyZ1md8G/IgAYFDO6jGc9MwWR3N9UK22W6Es f+/MMJeHuztWLcjSnlC7AVx1sOGzYTC5V8w6BfsBILdAuUXmfCYUnNKW7dQO6DhR+AhK Vksg== X-Gm-Message-State: AMke39myr2v4aGOKQrUOpK+iRw4wAKKr34g2NPYpGZ5sSC1VHgucEPaD3VXl2CgxEv6qXQ== X-Received: by 10.25.169.14 with SMTP id s14mr2021166lfe.3.1488825208323; Mon, 06 Mar 2017 10:33:28 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.28.207.206 with SMTP id f197ls481250wmg.22.gmail; Mon, 06 Mar 2017 10:33:17 -0800 (PST) X-Received: by 10.28.31.139 with SMTP id f133mr15230775wmf.25.1488825197629; Mon, 06 Mar 2017 10:33:17 -0800 (PST) Original-Received: from mail-wm0-x232.google.com (mail-wm0-x232.google.com. [2a00:1450:400c:c09::232]) by mx.google.com with ESMTPS id e8si18807041wre.85.2017.03.06.10.33.17 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 06 Mar 2017 10:33:17 -0800 (PST) Received-SPF: pass (google.com: domain of daniel.kruegler@gmail.com designates 2a00:1450:400c:c09::232 as permitted sender) client-ip=2a00:1450:400c:c09::232; Original-Received: by mail-wm0-x232.google.com with SMTP id v186so71363346wmd.0 for ; Mon, 06 Mar 2017 10:33:17 -0800 (PST) X-Received: by 10.28.218.80 with SMTP id r77mr14343750wmg.0.1488825197185; Mon, 06 Mar 2017 10:33:17 -0800 (PST) Original-Received: by 10.28.47.211 with HTTP; Mon, 6 Mar 2017 10:33:16 -0800 (PST) In-Reply-To: <52147c7c-ff38-4eaf-9f73-7f40628e9d58@isocpp.org> 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::232 as permitted sender) smtp.mailfrom=daniel.kruegler@gmail.com; dmarc=pass (p=NONE sp=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:31456 Archived-At: 2017-03-06 18:43 GMT+01:00 : > Following my question on SO, I'd like to propose changing the data() method > of std::array to return a reference to the underlying C-array instead of > returning a raw pointer. > This would allow backwards compatibility with older functions which accept a > reference/pointer to a C-array of a known size. > Currently, if you use an std::array, and have such a function, there is no > way AFAIK to call it on the underlying C-array without a reinterpret_cast. > > I see no real disadvantage to this change - if you really want, you can > always decay the C-array reference to a raw pointer reference. > > Or at least, in case it's considered valuable to keep the data() method > which returns the raw pointer by value, I suggest adding a c_array() method > instead which returns a reference to the C-array. Exactly this had been suggested in the past, but failed: http://cplusplus.github.io/LWG/lwg-closed.html#930 If you want it, this requires a proposal. Some previous arguments against it ("[..] until we have implementation experience with reference qualifiers") are mood now, but nonetheless the proposal should try to give a good rationale for it. 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/CAGNvRgAwqbp%3DZrDSCFAWPc%3DKAviqPa%2BBx9XEL-3fvtqy2%3DVS1w%40mail.gmail.com. .