220 7336 article Path: news.gmane.org!not-for-mail From: "Billy O'Neal" Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Suggestion: ostringstream::move_str() Date: Wed, 16 Oct 2013 19:38:04 -0700 Lines: 162 Approved: news@gmane.org Message-ID: References: <8d70b552-2ec1-45e7-9afb-dee28d73438a@isocpp.org> <4291267.ToRBPx4CWi@tjmaciei-mobl2> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary=089e0158a92e6e99da04e8e6b72a X-Trace: ger.gmane.org 1381977521 32589 80.91.229.3 (17 Oct 2013 02:38:41 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 17 Oct 2013 02:38:41 +0000 (UTC) To: std-proposals Original-X-From: std-proposals+bncBDKLBLVE6ADBBNE37WJAKGQEEUFKJ3I@isocpp.org Thu Oct 17 04:38:47 2013 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ie0-f199.google.com ([209.85.223.199]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1VWdU6-0002FW-PJ for gclcip-std-proposals@m.gmane.org; Thu, 17 Oct 2013 04:38:47 +0200 Original-Received: by mail-ie0-f199.google.com with SMTP id qd12sf4465692ieb.6 for ; Wed, 16 Oct 2013 19:38:45 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; 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=TItI1Aa+9BVljhpjy/PTkndP1OzOrmn33zDKvhf2ji0=; b=RVl26KDWWl7yLJBx9lPRvR1JP2ZB0pbqAJxKlJbjzR/xmPWUaiO9xBZXWxOuJH8M5W B5IG7ZKPPM8D2f/p9xB65N/w8hNusr+HpDxpMQA/bnF5WXw/uzux3BP5KINZxuKJ5wE2 xzONhWUv0NW7s5FiyD/y2ScdU6Aaja3E48TmpRPbPaqV/Ech1aSLBl84Buo0DD3Qkre9 rxLo4U1S+6KdPArloBmTTf5OMNL5eAZ+L8vkWmIc/uG8H676YkIAFeOAaQHBN60eVC+U pohcSBseUXwNYkH0/t3gAtpK1t2CR2MwPrwg6FPeNkGxGKc6gO404EsZZX+FwAenco6S VooA== X-Received: by 10.50.3.40 with SMTP id 8mr364045igz.1.1381977525776; Wed, 16 Oct 2013 19:38:45 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.182.241.168 with SMTP id wj8ls255330obc.57.gmail; Wed, 16 Oct 2013 19:38:44 -0700 (PDT) X-Received: by 10.182.40.134 with SMTP id x6mr10040400obk.31.1381977524686; Wed, 16 Oct 2013 19:38:44 -0700 (PDT) Original-Received: from mail-ob0-x233.google.com (mail-ob0-x233.google.com [2607:f8b0:4003:c01::233]) by mx.google.com with ESMTPS id ii9si7013957obc.102.1969.12.31.16.00.00 (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 16 Oct 2013 19:38:44 -0700 (PDT) Received-SPF: pass (google.com: domain of billy.oneal@gmail.com designates 2607:f8b0:4003:c01::233 as permitted sender) client-ip=2607:f8b0:4003:c01::233; Original-Received: by mail-ob0-f179.google.com with SMTP id wp18so1386051obc.10 for ; Wed, 16 Oct 2013 19:38:44 -0700 (PDT) X-Received: by 10.182.99.231 with SMTP id et7mr10143312obb.10.1381977524441; Wed, 16 Oct 2013 19:38:44 -0700 (PDT) Original-Received: by 10.182.87.37 with HTTP; Wed, 16 Oct 2013 19:38:04 -0700 (PDT) In-Reply-To: <4291267.ToRBPx4CWi@tjmaciei-mobl2> X-Original-Sender: billy.oneal@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of billy.oneal@gmail.com designates 2607:f8b0:4003:c01::233 as permitted sender) smtp.mail=billy.oneal@gmail.com; dkim=pass header.i=@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:7336 Archived-At: --089e0158a92e6e99da04e8e6b72a Content-Type: text/plain; charset=ISO-8859-1 Is an implementation permitted to add an overload like this? string*&&* str() *&&* { /* ... */ } Billy O'Neal https://github.com/BillyONeal/ http://stackoverflow.com/users/82320/billy-oneal Malware Response Instructor - BleepingComputer.com On Wed, Oct 16, 2013 at 7:05 PM, Thiago Macieira wrote: > On quarta-feira, 16 de outubro de 2013 18:46:18, jgottman6@gmail.comwrote: > > The method os.str() returns a string that is a copy of the collected > state > > of the ostringstream. It has to be, because it is possible to write more > > values to os later. But in this function, it is not necessary to > maintain > > the state of the ostringstream, since it is about to be destructed > anyway. > > It would therefore be very nice to be able to return a version of > > ostringstream::str() that steals the guts of the ostringstream, using > > something like move semantics, and uses them to construct the returned > > string more efficiently than by a copy Is this technically feasible? > > > > Joe Gottman > > This was discussed in the past month. > > The problem is that the standard does not require ostringstream to be > actually > backed by a string. It might use different kinds of buffers, including > multiple > ones. Therefore, it's not possible to mandate that it actually moves > anything. > > At best, we could add a way to potentially do it, but not guarantee that. > > -- > 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 > > -- > > --- > 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/. > -- --- 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/. --089e0158a92e6e99da04e8e6b72a Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
Is an implementation permitted to add an overload like thi= s?

string&& str() &&
=
{
=A0 =A0 =A0/* ... */
}

Billy O'Neal
Malware Response Instructor - BleepingComputer.com


On Wed, Oct 16, 2013 at 7:05 PM, Thiago = Macieira <thiago@macieira.org> wrote:
On quarta-feira, 16 de outubro de 2013 18:46:18, jgottman6@gmail.com wrote:
> The method os.str() returns a string that is a copy of the collected s= tate
> of the ostringstream. =A0It has to be, because it is possible to write= more
> values to os later. =A0But in this function, it is not necessary to ma= intain
> the state of the ostringstream, since it is about to be destructed any= way.
> It would therefore be very nice to be able to return a version of
> ostringstream::str() that steals the guts of the ostringstream, using<= br> > something like move semantics, and uses them to construct the returned=
> string more efficiently than by a copy =A0Is this technically feasible= ?
>
> Joe Gottman

This was discussed in the past month.

The problem is that the standard does not require ostringstream to be actua= lly
backed by a string. It might use different kinds of buffers, including mult= iple
ones. Therefore, it's not possible to mandate that it actually moves an= ything.

At best, we could add a way to potentially do it, but not guarantee that.
--
Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
=A0 =A0Software Architect - Intel Open Source Technology Center
=A0 =A0 =A0 PGP/GPG: 0x6EF45358; fingerprint:
=A0 =A0 =A0 E067 918B B660 DBD1 105C =A0966C 33F5 F005 6EF4 5358

--

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To post to this group, send email to std-proposals@isocpp.org.
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