220 14951 <1dddd305-0b0d-47ff-b425-20ce1e1ff6e0@isocpp.org> article Path: news.gmane.org!not-for-mail From: sasho648 Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Earlier creation of function return-value. Date: Wed, 10 Dec 2014 12:35:57 -0800 (PST) Lines: 219 Approved: news@gmane.org Message-ID: <1dddd305-0b0d-47ff-b425-20ce1e1ff6e0@isocpp.org> References: <3c0ee2e3-8706-44b0-a3d2-985e494dd8ac@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_863_1198208871.1418243757276" X-Trace: ger.gmane.org 1418243768 7376 80.91.229.3 (10 Dec 2014 20:36:08 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 10 Dec 2014 20:36:08 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDBNZXHN2QPRBLO5UKSAKGQE7F37TNA@isocpp.org Wed Dec 10 21:36:00 2014 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ig0-f199.google.com ([209.85.213.199]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1XynzK-0002Ck-Uv for gclcip-std-proposals@m.gmane.org; Wed, 10 Dec 2014 21:35:59 +0100 Original-Received: by mail-ig0-f199.google.com with SMTP id hl2sf17356438igb.10 for ; Wed, 10 Dec 2014 12:35:58 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:date:from:to:message-id:in-reply-to:references :subject:mime-version:content-type:x-original-sender:reply-to :precedence:mailing-list:list-id:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=pcK/oHlESjmOb83mAfjyj4Om8NfVvUEtZkecuCcyE6U=; b=b4bAfPjhXfSq+N98kg1E/4I+2SAhZeUvKH5GVJvDTJ+pZDIfJF3hkMikyFEwfIY0Ee 0QcNRnyV3lgALZ36tBdT4eRygzq5Jb5pOBdCCcs1gMza1NKvG1dTWQV2zWJztOVcALZ6 LSPvtascTUoG7CQphHVyIw/oGHdgJ5x9fO8UCB1/JcL/qrWaQ9ditiOKH+zNZPuRWSwY 3jc96NwO61g+wVRgeyrl9C8z3quMremwoJ9Ptvb1nyk3+1bUm4Zzz5y9B2A7H1wchmnz /NXcm3guImiAxAw2CfOaOH/2zgmpDhFrGZYZ9kpEIQabCiSo1lXY6buI3zZN/4bGsFK6 e4HA== X-Gm-Message-State: ALoCoQnbJTpddHnQnnzhIwkGjSu1yy9oQU4uNXBYdZ0NcGP4wqwaQr2nen+HAepNa39GSCnPbhNc X-Received: by 10.182.65.232 with SMTP id a8mr5607149obt.5.1418243758355; Wed, 10 Dec 2014 12:35:58 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.140.94.209 with SMTP id g75ls787980qge.75.gmail; Wed, 10 Dec 2014 12:35:57 -0800 (PST) X-Received: by 10.140.94.150 with SMTP id g22mr134453qge.0.1418243757805; Wed, 10 Dec 2014 12:35:57 -0800 (PST) In-Reply-To: <3c0ee2e3-8706-44b0-a3d2-985e494dd8ac@isocpp.org> X-Original-Sender: sasho648@mail.bg 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:14951 Archived-At: ------=_Part_863_1198208871.1418243757276 Content-Type: multipart/alternative; boundary="----=_Part_864_1342336978.1418243757276" ------=_Part_864_1342336978.1418243757276 Content-Type: text/plain; charset=UTF-8 Never mind. It seems I actually find a way to implement this without the need of introducing a new syntax by using class constructors like this: struct FunctionReturningS { explicit FunctionReturningS(bool b) { S temp; //store some data at 'temp' and 'return_value' temp.pSomeMemory[0] = '9'; return_value.pSomeMemory[5] = '6'; if(!b) return; //just exit the function (temp1 is replaced by 'return_value') return_value.~S(); //calling explicit destructor on 'return_value' new (&return_value) S((S &&)temp); //placement new, re-constructs 'return_value' by 'temp' } S return_value; }; So you can instance the function like: int main() { auto &&RetValue = FunctionReturningS(true).return_value; cout << RetValue.pSomeMemory[0] << endl; auto &&RetValue1 = FunctionReturningS(false); return 0; } Thanks for your opinions anyway. -- --- 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_864_1342336978.1418243757276 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Never mind. It seems I actually find a way to implement th= is without the need of introducing a new syntax by using class constructors= like this:

struct FunctionReturningS
{
    explicit FunctionReturningS(bool b)
    {=
        S temp;

        //store some data at 'temp' = and 'return_value'

        temp.pSomeMemory[0] =3D '9';

        r= eturn_value.pSomeMem= ory[5] =3D '6';=

        if(!b) = return; //just exit the function (temp1 is re= placed by 'return_value')

        return_value.~S(); //calling explicit destructor on 'return_value'

 =       new (&am= p;return_v= alue) S((S &&)temp); //placement new, re-constructs 'return_value' by 'temp'
  &nbs= p; }


&nbs= p;   S return_value;
}= ;

So you can instance the func= tion like:

int main()
{
    auto &&RetValue =3D FunctionReturningS(true).return_value;

    cout << RetValue.pSomeMemory[0] <<= endl;

    auto<= span style=3D"color: #000;" class=3D"styled-by-prettify"> &&RetValue1 =3D FunctionReturningS(false);

    return 0;
}


Thanks for your opinions anyway.

--

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