220 7334 <8d70b552-2ec1-45e7-9afb-dee28d73438a@isocpp.org> article Path: news.gmane.org!not-for-mail From: jgottman6@gmail.com Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Suggestion: ostringstream::move_str() Date: Wed, 16 Oct 2013 18:46:18 -0700 (PDT) Lines: 87 Approved: news@gmane.org Message-ID: <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: multipart/alternative; boundary="----=_Part_370_21974380.1381974378963" X-Trace: ger.gmane.org 1381974378 30409 80.91.229.3 (17 Oct 2013 01:46:18 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 17 Oct 2013 01:46:18 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBD7LHGWIQEPRB3EC7WJAKGQECTBGT5I@isocpp.org Thu Oct 17 03:46:23 2013 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ob0-f199.google.com ([209.85.214.199]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1VWcfO-0001oJ-Np for gclcip-std-proposals@m.gmane.org; Thu, 17 Oct 2013 03:46:23 +0200 Original-Received: by mail-ob0-f199.google.com with SMTP id vb8sf4607518obc.6 for ; Wed, 16 Oct 2013 18:46:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=date:from:to:message-id:subject:mime-version:x-original-sender :reply-to:precedence:mailing-list:list-id:list-post:list-help :list-archive:list-subscribe:list-unsubscribe:content-type; bh=hJ5rjSXplTvlHdGU7bU+u1ZKhJKsodwTzN5wPrft6NY=; b=rLd/tb8+N28VvRDMF/O04vn6BP+esT5IG6rDgcDjT0Zs61w+doevW+dYkV5rL80SqJ xDok2RF6WMeqgCxbCI95KoBbjY5Or+IFHUzKr26x9iyN2G8GhOtksre4yKNw+9hCMmsC Hx7uFlAjYr8RaWNV+m72dgaw45jnv/6JJOxHa3KelIAwOCUTykOQcLIxNsJiuWtnKJ4/ 5Bch+6ywanH8x1J/BhshNgxsmVOxg3JurdaHnsVw+lCS0WCPCnR0pHZfTGMir+5k7h2q 8PNaGMsr5vKRJEodHjK/IipbpuykXHIxSNcd2inFxJvxezBXamkVyJtvI/b16wvWDBgB cmYQ== X-Received: by 10.182.109.164 with SMTP id ht4mr2159797obb.16.1381974381734; Wed, 16 Oct 2013 18:46:21 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.50.107.38 with SMTP id gz6ls3574134igb.2.canary; Wed, 16 Oct 2013 18:46:20 -0700 (PDT) X-Received: by 10.50.9.33 with SMTP id w1mr158410iga.12.1381974380379; Wed, 16 Oct 2013 18:46:20 -0700 (PDT) X-Original-Sender: jgottman6@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:7334 Archived-At: ------=_Part_370_21974380.1381974378963 Content-Type: text/plain; charset=ISO-8859-1 A common use-case for std::ostringstream is to to do something like the following: std::string foo() { std::ostringstream os; /// write values to os return os.str(); } 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 -- --- 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/. ------=_Part_370_21974380.1381974378963 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
A common use-case for std::ostringstream is to to do somet= hing like the following:

std::string foo() {
   std::ostringstream os;
   /// write values to os
  &= nbsp;retur= n os.str();
}

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 lat= er.  But in this function, it is not necessary to maintain the state o= f the ostringstream, since it is about to be destructed anyway.  It wo= uld 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 Gottm= an

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