220 14122 <6e2cf992-2bc8-4334-8ea2-df947fc7d884@isocpp.org> article Path: news.gmane.org!not-for-mail From: Olaf van der Spek Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Reconstruct function idea Date: Wed, 22 Oct 2014 08:31:56 -0700 (PDT) Lines: 93 Approved: news@gmane.org Message-ID: <6e2cf992-2bc8-4334-8ea2-df947fc7d884@isocpp.org> References: <8a74f08b-7453-4d1a-9f20-bc1d3866617c@isocpp.org> <27e2ae9c-8b1f-4688-9bb3-9caef6bf4f54@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_3781_220329307.1413991916580" X-Trace: ger.gmane.org 1413991925 3373 80.91.229.3 (22 Oct 2014 15:32:05 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 22 Oct 2014 15:32:05 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBC5NB45SSABBB3M3T6RAKGQEO2WP6DY@isocpp.org Wed Oct 22 17:31:59 2014 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-yh0-f71.google.com ([209.85.213.71]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1XgxtG-0006Lv-8S for gclcip-std-proposals@m.gmane.org; Wed, 22 Oct 2014 17:31:58 +0200 Original-Received: by mail-yh0-f71.google.com with SMTP id f10sf5207896yha.2 for ; Wed, 22 Oct 2014 08:31:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=date:from:to:message-id:in-reply-to:references: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=r64Bf1Po7qgLTvjPE+CBCcNHcOqDXLh7IGfXBEnfZ7Q=; b=e23FNaZiR9wxYZuPbfFoSzkgq0FMbuF8ESXNfB3i5knXB7bSyo6kYiNeS+CwwR5jKd rF8gSHiWwQL5HuZ58Jknvnhp0y1t7sEc04/cmb0as2UGm4/zlTT8WLVMVN+rT93W2HA4 Y2Ynr0eGeeXla3qTTJLpYZlo34h6y4D2hnIamsGRmIpdljIYIsva1iTtKHYXxHtAcNsV c9PuzYVMBOKv4VdbZTDEiRBjlbq3xgBNwmvNHCIeApxjP3NGochPdrt4FhPtqEVixufv Q7kUIB70GEHcIBzqulHEhsAVN/Ax36bhPXjNxL1QyBEapwiwHrm5wCDKYbNHFdW/7gf5 37eg== 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:x-original-sender:reply-to:precedence :mailing-list:list-id:list-post:list-help:list-archive :list-subscribe:list-unsubscribe:content-type; bh=r64Bf1Po7qgLTvjPE+CBCcNHcOqDXLh7IGfXBEnfZ7Q=; b=NqJ+Y1Jopk1gUzKEHZIc5V1zNayYSQkFWYURw+GrsIrTfW4fHNc8vDTFTPi43l5rno utJ6AUqlApFApTVquTGsNfpkJrZdEg9GlVXAq7I91KG9rha9XJPc5VhW4ifJNTl2fJuk CdS3pKhhf4YrzB6G0jwMxfbbeSiOou+1Rwhflu9Z4bh3KX3y2NJGcU0+/42HF00F+13Q IbMm+Nl3ZEo/jp33TaXfZl/vv1Y3P+Orn5RT05PlQ4U+s/ZAW0WjIxUh7mGdEGguCbo2 nguiRwYNrrv+e+KgJWkohbrYQ7L+tfQIrLwT1XspZdk32V+6FlpDrw97yRa2n4RZufFO D/cw== X-Gm-Message-State: ALoCoQkKLgfoaR27CwQJLvYrC4kLptLZZ5ousixskD3iAKAi8vAfQkARL75bJByCYGTi70DJyTkS X-Received: by 10.236.66.102 with SMTP id g66mr27225298yhd.3.1413991917448; Wed, 22 Oct 2014 08:31:57 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.140.40.232 with SMTP id x95ls810574qgx.76.gmail; Wed, 22 Oct 2014 08:31:56 -0700 (PDT) X-Received: by 10.140.109.132 with SMTP id l4mr17028qgf.24.1413991916914; Wed, 22 Oct 2014 08:31:56 -0700 (PDT) In-Reply-To: <27e2ae9c-8b1f-4688-9bb3-9caef6bf4f54@isocpp.org> X-Original-Sender: olafvdspek@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:14122 Archived-At: ------=_Part_3781_220329307.1413991916580 Content-Type: text/plain; charset=UTF-8 On Thursday, October 16, 2014 12:22:53 AM UTC+2, Myriachan wrote: > > The main reason to use something like this is for copy constructors. > Sometimes, the most convenient way to implement a copy or move constructor > is like this: > > T &T::operator =(const T ©) > { > if (© != this) > { > this->~T(); > new(this) T(copy); > } > return *this; > } > > ...and equivalently with std::forward for move constructors. > > Can't you forward to the assignment operator in that case (most of the time)? -- --- 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_3781_220329307.1413991916580 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
On Thursday, October 16, 2014 12:22:53 AM UTC+2, Myriachan= wrote:
T= he main reason to use something like this is for copy constructors.  S= ometimes, the most convenient way to implement a copy or move constructor i= s like this:

T &T::operator =3D(const T &copy)
{
    if (&copy !=3D this)
    {
        this->~T();
        new(this) T(copy);=
    }
    return *this;
}

...and equivalently w= ith std::forward for move constructors.


Can't you forward to the assignment operator in that case = (most of the time)? 

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