220 7342 <8091853.8bdkahh1DX@tjmaciei-mobl2> article Path: news.gmane.org!not-for-mail From: Thiago Macieira Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Suggestion: ostringstream::move_str() Date: Wed, 16 Oct 2013 23:31:53 -0700 Lines: 73 Approved: news@gmane.org Message-ID: <8091853.8bdkahh1DX@tjmaciei-mobl2> References: <8d70b552-2ec1-45e7-9afb-dee28d73438a@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 Content-Transfer-Encoding: quoted-printable X-Trace: ger.gmane.org 1381991511 3545 80.91.229.3 (17 Oct 2013 06:31:51 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 17 Oct 2013 06:31:51 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCB4TK757YBRBW4I72JAKGQERVJCPDA@isocpp.org Thu Oct 17 08:31:57 2013 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-lb0-f199.google.com ([209.85.217.199]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1VWh7k-0002Kw-Qh for gclcip-std-proposals@m.gmane.org; Thu, 17 Oct 2013 08:31:56 +0200 Original-Received: by mail-lb0-f199.google.com with SMTP id z5sf2151511lbh.2 for ; Wed, 16 Oct 2013 23:31:56 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=from:to:subject:date:message-id:user-agent:in-reply-to:references :mime-version: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-transfer-encoding:content-type; bh=8JQBBAGbXwuMBWyE4JwfRZjjCMAf4gMA2BkZENWrLHQ=; b=NH17nDABOFdWfdk0H1x3L9LVBR/kHEWo72mjJ76TSaCekm3e6RynUqhn5uA39FDYwD M1HARypcQXjlhuyVAlu/vwQr2v/XgkwOaCQeXTTYNRDHO0oTG1IUHHKOHw9cvnhui9ha 9NIQB6yP76QESrpLMPP6fKyu0vcqpkpc4D1k4N3KanzlnuZ3fuROBGN3KkXa6IeL2OHZ AJvq+b7xgM6KCwxI8WmeqULhnpShlxpgEFKU0tD2vyJEKg7QGAAy13YTIf4NBCUU1Ffi FFmPj/RoDJ+qpRRZo8mGIYRTNuFEwqofmb88Sa7qGZm8FGNckSqsobGTPmaSGq8iWkEE v1rA== X-Received: by 10.152.25.161 with SMTP id d1mr2415758lag.7.1381991516097; Wed, 16 Oct 2013 23:31:56 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.180.182.169 with SMTP id ef9ls360829wic.30.gmail; Wed, 16 Oct 2013 23:31:55 -0700 (PDT) X-Received: by 10.15.35.67 with SMTP id f43mr251890eev.100.1381991515320; Wed, 16 Oct 2013 23:31:55 -0700 (PDT) Original-Received: from gondolin.macieira.info (gondolin.macieira.info. [2a01:4f8:d13:f81:21c:14ff:fe01:12a3]) by mx.google.com with ESMTP id b42si64312047eem.342.1969.12.31.16.00.00; Wed, 16 Oct 2013 23:31:55 -0700 (PDT) Received-SPF: pass (google.com: domain of thiago@macieira.org designates 2a01:4f8:d13:f81:21c:14ff:fe01:12a3 as permitted sender) client-ip=2a01:4f8:d13:f81:21c:14ff:fe01:12a3; Original-Received: from tjmaciei-mobl2.localnet (unknown [IPv6:2a01:4f8:d13:f81:21c:14ff:fe01:12a3]) by gondolin.macieira.info (Postfix) with ESMTPSA id BF60012C005 for ; Wed, 16 Oct 2013 23:31:54 -0700 (PDT) User-Agent: KMail/4.12 pre (Linux/3.9.10-100+i915fix.fc17.x86_64; KDE/4.11.60; x86_64; git-8054221; 2013-08-01) 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 2a01:4f8:d13:f81:21c:14ff:fe01:12a3 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:7342 Archived-At: On quinta-feira, 17 de outubro de 2013 08:02:12, Daniel Kr=FCgler wrote: > Implementations have already great freedom to play around with member > functions overloads as denoted by [member.functions] p2. The intention > is to make above kind of addition possible, but the current wording > has not been updated in regard to ref-qualified member functions yet, > see the third bullet in >=20 > http://cplusplus.github.io/LWG/lwg-active.html#2259 There are two important differences there. First, the wording allows one to add overloads, to provide a function with= =20 more parameters, provided they're defaulted, or to split a function with=20 default parameters into more than one. In order to add a ref qualifier=20 overload, however, it requires changing the existing members. Second, and more importantly, the recommendation is a guideline for how one= =20 can write an implementation. The discussion here would *require* all=20 implementations to modify their already-existing ABI. That's *exactly* the problem I had last week when I tried to implement an= =20 rvalue-non-const QString::toLatin1. The solution I came up with is not pret= ty: https://codereview.qt-project.org/67728 https://codereview.qt-project.org/68300 Instead, maybe we can solve this by adding a pair of non-const new members = to=20 stringstream: /* note how implementors may choose to implement the following * function as actually two */ string reset(const string &newstring =3D string()) { string tmp =3D str(); str(newstring); return tmp; } string reset(string &&newstring) { string tmp =3D str(); str(move(newstring)); return tmp; } The wording in the spec should say that it returns the current string and= =20 resets the buffer to the provided argument and that nothing more is require= d. Implementations that store an actual string inside the basic_stringbuf may= =20 optimise by inserting move operations. They might look like this: string reset(const string &newstring =3D string()) { swap(newstring, _M_stringbuf._M_string); return newstring;} string reset(string &&newstring) { swap(newstring, _M_stringbuf._M_string); return newstring;} --=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/. .