220 15645 article Path: news.gmane.org!not-for-mail From: jgottman6@gmail.com Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: RFC: Adding Symmetry Between shared_ptr and weak_ptr Date: Tue, 13 Jan 2015 15:24:46 -0800 (PST) Lines: 100 Approved: news@gmane.org Message-ID: References: Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_4880_1837022587.1421191486289" X-Trace: ger.gmane.org 1421191496 31179 80.91.229.3 (13 Jan 2015 23:24:56 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 13 Jan 2015 23:24:56 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBD7LHGWIQEPRBPWS22SQKGQER3OTTFQ@isocpp.org Wed Jan 14 00:24:49 2015 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-oi0-f71.google.com ([209.85.218.71]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1YBApM-0004r8-8Y for gclcip-std-proposals@m.gmane.org; Wed, 14 Jan 2015 00:24:48 +0100 Original-Received: by mail-oi0-f71.google.com with SMTP id u20sf26819480oif.2 for ; Tue, 13 Jan 2015 15:24:47 -0800 (PST) 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 :content-type:x-original-sender:reply-to:precedence:mailing-list :list-id:list-post:list-help:list-archive:list-subscribe :list-unsubscribe; bh=pMX1ykqUn6tXFyGFCIC6kABCjyRr7dXnzXZ5V4RvjbE=; b=y3HY7IV0V5aSsyHTgeENsxZJ2dn7wXdQxXRCM3xyljhMv3BzSa7VthY5h/xb6JqCkr 9f7qmlzcLJ9E5+DWqeMlI58DarVCuq+osM97u5ERD4LipXsoAEghHkFmLuGS22ju/O2w RlZtV+FocGASgyR2NORkv0JL/sUQRriz+AF3WzmTOl7YAJbumf5pbLXhFIDJM+nuNkyf lWTi0NfF1ZzXJNXnpr3zCvdw1q2s9xgbFAO34JbEPbSUgf3oQkT6oDq81e8/joyeSu5N 23LXv0xbUq9pGwV3tuiF+iA0fEGKfyfIbqIs15vGCdwx/ZExahohS1JnzxcWE6RLaqBn QbsQ== 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=pMX1ykqUn6tXFyGFCIC6kABCjyRr7dXnzXZ5V4RvjbE=; b=isxI736DGiZK2XjbtPE02tQTnOtsNGKQXPInuLmPmi2PD9gKChpdzafWVT5+p1QMHa C4m2sa7PyFdQSzUcaPGP0PT42nvKJnjGHSB+sK5U5HjebAo44iwT9pwRr4cWVlBpSLcb mS1jEN9stckv0oQQrVGiC/HNKFyMbrnbLx4VwifQo6tI5m6l34+dMp0BhqCxNfQSUCEL vsyBVUZjVivhHlgNR7/KYKymr8nwziBfZkoVmfxn/LjnCBglHq9O9+eS2wEllSu9TyST smY2uC+V+WotXUk5ZVwph3mXRhtNdRlkaLH395MSj8SoSDqu9Ma8FjrvSlGmUX+Jaqc4 ak1Q== X-Gm-Message-State: ALoCoQn8L7o3h7LMSnlv39lBLkH5KSUu9sc2c41Mhx/hA72B3ONjsel8PWA0ieFt0kaePxm8gnWS X-Received: by 10.42.54.76 with SMTP id q12mr1692196icg.13.1421191487435; Tue, 13 Jan 2015 15:24:47 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.140.22.163 with SMTP id 32ls243860qgn.48.gmail; Tue, 13 Jan 2015 15:24:46 -0800 (PST) X-Received: by 10.140.98.132 with SMTP id o4mr764qge.41.1421191486727; Tue, 13 Jan 2015 15:24:46 -0800 (PST) In-Reply-To: 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:15645 Archived-At: ------=_Part_4880_1837022587.1421191486289 Content-Type: multipart/alternative; boundary="----=_Part_4881_466226790.1421191486289" ------=_Part_4881_466226790.1421191486289 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Just one minor quibble. I don't see the use case for the weak_ptr overload= =20 that takes a pointer and a weak_ptr. The pointer should always be some=20 kind of sub-object of an object pointed to by a shared_ptr, such as a data= =20 member or container element. For you to have this pointer and know that it= =20 is still valid, you should still have access to the shared_ptr owning it. = =20 Therefore, you should be able to construct your new weak_ptr from the=20 pointer and the shared_ptr. Joe Gottman On Saturday, January 10, 2015 at 2:01:54 PM UTC-5, Arthur O'Dwyer wrote: > > I've got a rough draft of a proposal for the next meeting in May, and=20 > would like to hear anyone's feedback on the format and content before the= n. > > https://quuxplusone.github.io/draft/Nweak_ptr_proposal.html > > The TL;DR is that it proposes two very small new library features: > - shared_ptr::unlock(), which turns a shared_ptr into a weak_ptr,=20 > symmetric with weak_ptr::lock() > - An two-argument constructor for weak_ptr(), symmetric with shared_ptr's= =20 > two-argument constructor > > =E2=80=93Arthur > --=20 ---=20 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 e= mail 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-proposa= ls/. ------=_Part_4881_466226790.1421191486289 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Just one minor quibble.  I don't see the use case for= the weak_ptr overload that takes a pointer and a weak_ptr.  The point= er should always be some kind of sub-object of an object pointed to by a sh= ared_ptr, such as a data member or container element.  For you to have= this pointer and know that it is still valid, you should still have access= to the shared_ptr owning it.  Therefore, you should be able to constr= uct your new weak_ptr from the pointer and the shared_ptr.

Joe Gottm= an

On Saturday, January 10, 2015 at 2:01:54 PM UTC-5, Arthur O'Dwyer= wrote:
I= 've got a rough draft of a proposal for the next meeting in May, and would = like to hear anyone's feedback on the format and content before then.
=

https://= quuxplusone.github.io/draft/Nweak_ptr_proposal.html

The TL;DR is that it proposes two very small new library features:=
- shared_ptr::unlock(), which turns a shared_ptr into a weak_ptr= , symmetric with weak_ptr::lock()
- An two-argument constructor f= or weak_ptr(), symmetric with shared_ptr's two-argument constructor

=E2=80=93Arthur

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