220 41437 <91aa6796-9935-4a02-8021-0e35264811a0@isocpp.org> article Path: news.gmane.org!.POSTED.blaine.gmane.org!not-for-mail From: dcrc2cpp@gmail.com Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Destructive move, via forwarding and destructuring operations Date: Sat, 9 Feb 2019 11:22:56 -0800 (PST) Approved: news@gmane.org Message-ID: <91aa6796-9935-4a02-8021-0e35264811a0@isocpp.org> References: <7b2204ba-51d0-481e-9974-10029547031c@isocpp.org> Reply-To: std-proposals@isocpp.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_61_307303625.1549740176606" Injection-Info: blaine.gmane.org; posting-host="blaine.gmane.org:195.159.176.226"; logging-data="109725"; mail-complaints-to="usenet@blaine.gmane.org" Cc: dcrc2cpp@gmail.com To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBCH4BCOOUIFRBEOR7TRAKGQE62ARDVI@isocpp.org Sat Feb 09 20:23:01 2019 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-yb1-f200.google.com ([209.85.219.200]) by blaine.gmane.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.89) (envelope-from ) id 1gsYDM-000SNY-Kn for gclcip-std-proposals@m.gmane.org; Sat, 09 Feb 2019 20:23:00 +0100 Original-Received: by mail-yb1-f200.google.com with SMTP id t3sf4707900ybo.15 for ; Sat, 09 Feb 2019 11:23:00 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc: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; bh=QwW2EZr25byDNQAENAzJW0WkXp9XH3PHiYkfxnIhgSc=; b=yljoPCPWLMP+ROqhKfy3ZWSDhYkiP9/9vraSsAuMPLkOqVm7FCCDDUfecksNZVcvlO Ceq3GjtKxArslla2seun/rK35QULDzq0p1v6CLWEH5AecITQbNtFFwTqM1OA/Wh4e/TJ jO1UNV/bZ4cUTj2Zr7USbfSU1AoFgyCt/+NPqu9glxeaN1zTOJ0fK6hxR+QuPAmAsU2w 3KFJ4+JLBeCQpoPQBlB0fA5o3btjfOUeVVpT+gc6BfTrRVW58SpypKjdVeVWp32xdUP5 HmlXeRp6M6W4GxY5DinGyta/Ko9jhSOHQkT9fzUGCbcfYRaB6rvKD9h59reI56gMuU95 /PUg== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc: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; bh=QwW2EZr25byDNQAENAzJW0WkXp9XH3PHiYkfxnIhgSc=; b=fLPzs/bFGq+E9xOM4RR7k163IgxRk/7dcXUa3lVcoCbJSuELw1HTNgzgG/o9Hj0qaq Zd2rFeibWhJeG/CsdrhcD2Q7+Bn9FejFSVE+REGtCl7N39uXryWIB9YpE7ObfNghODna jL+9lUD7CeW532pHQQsVp87LRT8cTFfCHwuq3zX/rjyzfPi389w5w8F0dXJCzd3c2cKu c2AKPHfya6sN03V3CoGR4aWXPLdZqtWYTY7w6SWyCStVh2v2/vq1LetLlOqNZFWtG7Lg gHY9kCJPqO02Yo9obdCAZxv6tOX+ZGkVO5l3+PqA3CRvP80fO/xRXGJdOrX4xYf0a5mk 91AA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:message-id:in-reply-to :references:subject:mime-version:x-original-sender:reply-to :precedence:mailing-list:list-id:x-spam-checked-in-group:list-post :list-help:list-archive:list-subscribe:list-unsubscribe; bh=QwW2EZr25byDNQAENAzJW0WkXp9XH3PHiYkfxnIhgSc=; b=esGkBE91ogpAYqPtfDwU0da0Q/flC+I7d58xqPDBlEum1d08vGDHE1N2kwmfFOZ5+V WOsNLFToiDFqWKrPF13o9Rj/jbbqV/VcZhF4MSWQ725oyP6bLVG5PaiovCSu71MwKBGH Q5VI31MglYeFXyzzt1C89F2hvbQdjyS+uqldtMGUoGkMW0ViN3s6zEzJ4Xu8ZpGyWsod cpxdsCNUAccGjcfFG02W/THX6wCDve11O5jPe4KysVGw4jrTtQhqBoa73Yudk0OCPG2d axuwuY10HjGH5DNHjHeO9pewvs1ycJi7rKv3sYZ2edtW+QfMCu6iLAk615zvL+AFLPHV in+Q== X-Gm-Message-State: AHQUAuadb0E/k7HhMwheoB4TvJRYZ9TiknO1i6QY5ROiVz0iOonh9bLC 6GXSiiWwcKJwl3iZKiWAxforaQ== X-Google-Smtp-Source: AHgI3IY/Qfvnnv2vpAJ1dqa3FhJxExL8zssgoXPkguDXIOPSIQu9hTX2N2tTqMNb4ZKitYiWuVt9sQ== X-Received: by 2002:a5b:3c2:: with SMTP id t2mr9602219ybp.48.1549740178611; Sat, 09 Feb 2019 11:22:58 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 2002:a25:d58:: with SMTP id 85ls2518546ybn.8.gmail; Sat, 09 Feb 2019 11:22:57 -0800 (PST) X-Received: by 2002:a5b:30c:: with SMTP id j12mr267470ybp.5.1549740177244; Sat, 09 Feb 2019 11:22:57 -0800 (PST) In-Reply-To: <7b2204ba-51d0-481e-9974-10029547031c@isocpp.org> X-Original-Sender: dcrc2cpp@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:41437 Archived-At: ------=_Part_61_307303625.1549740176606 Content-Type: multipart/alternative; boundary="----=_Part_62_919287694.1549740176606" ------=_Part_62_919287694.1549740176606 Content-Type: text/plain; charset="UTF-8" An updated version of this paper is now at https://github.com/dcrc2cpp/destructive-move The main change is that the role of "owning references" has been downplayed: owning reference variables have been renamed "moveable values", and they have been made more like non-reference variables. They can be initialized from an lvalue or rvalue reference, which was previously disallowed - this now calls the copy constructor or move constructor as appropriate, just as if a non-reference variable was being initialized. Also the behaviour of the forwarding operator has been rephrased in terms of changes to the scoping rules: the forwarding operator ends the scope of the reference that it applies to. Hopefully this better explains what is going on: the compiler does not have to track the lifetime of objects - the lifetime of an object is determined by the scope of the variable that refers to it. -- 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. To view this discussion on the web visit https://groups.google.com/a/isocpp.org/d/msgid/std-proposals/91aa6796-9935-4a02-8021-0e35264811a0%40isocpp.org. ------=_Part_62_919287694.1549740176606 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
An updated version of this paper is now at=C2=A0https://gi= thub.com/dcrc2cpp/destructive-move

The main change is th= at the role of "owning references" has been downplayed: owning re= ference variables have been renamed "moveable values", and they h= ave been made more like non-reference variables. They can be initialized fr= om an lvalue or rvalue reference, which was previously disallowed - this no= w calls the copy constructor or move constructor as appropriate, just as if= a non-reference variable was being initialized.

A= lso the behaviour of the forwarding operator has been rephrased in terms of= changes to the scoping rules: the forwarding operator ends the scope of th= e reference that it applies to. Hopefully this better explains what is goin= g on: the compiler does not have to track the lifetime of objects - the lif= etime of an object is determined by the scope of the variable that refers t= o it.

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To unsubscribe from this group and stop receiving emails from it, send an e= mail to std-proposa= ls+unsubscribe@isocpp.org.
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To view this discussion on the web visit https://groups.google.= com/a/isocpp.org/d/msgid/std-proposals/91aa6796-9935-4a02-8021-0e35264811a0= %40isocpp.org.
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