From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.devel Subject: Re: Lisp object that refers to a C struct Date: Wed, 17 Oct 2012 06:05:10 +0200 Message-ID: <83r4ox3frd.fsf@gnu.org> References: <83ehkz4edw.fsf@gnu.org> <83bog33wdr.fsf@gnu.org> <837gqq49j7.fsf@gnu.org> Reply-To: Eli Zaretskii NNTP-Posting-Host: plane.gmane.org X-Trace: ger.gmane.org 1350446767 7923 80.91.229.3 (17 Oct 2012 04:06:07 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 17 Oct 2012 04:06:07 +0000 (UTC) Cc: emacs-devel@gnu.org To: Stefan Monnier Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Wed Oct 17 06:06:11 2012 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1TOKtR-0006Ji-UI for ged-emacs-devel@m.gmane.org; Wed, 17 Oct 2012 06:06:06 +0200 Original-Received: from localhost ([::1]:49143 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TOKtK-0001Pt-SR for ged-emacs-devel@m.gmane.org; Wed, 17 Oct 2012 00:05:58 -0400 Original-Received: from eggs.gnu.org ([208.118.235.92]:38183) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TOKtH-0001ME-Tf for emacs-devel@gnu.org; Wed, 17 Oct 2012 00:05:56 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TOKtG-0006aa-VM for emacs-devel@gnu.org; Wed, 17 Oct 2012 00:05:55 -0400 Original-Received: from mtaout22.012.net.il ([80.179.55.172]:45135) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TOKtG-0006aB-Ns for emacs-devel@gnu.org; Wed, 17 Oct 2012 00:05:54 -0400 Original-Received: from conversion-daemon.a-mtaout22.012.net.il by a-mtaout22.012.net.il (HyperSendmail v2007.08) id <0MC000000RAZSN00@a-mtaout22.012.net.il> for emacs-devel@gnu.org; Wed, 17 Oct 2012 06:04:58 +0200 (IST) Original-Received: from HOME-C4E4A596F7 ([87.69.4.28]) by a-mtaout22.012.net.il (HyperSendmail v2007.08) with ESMTPA id <0MC000MQFRC9ZYG0@a-mtaout22.012.net.il>; Wed, 17 Oct 2012 06:04:58 +0200 (IST) In-reply-to: X-012-Sender: halo1@inter.net.il X-detected-operating-system: by eggs.gnu.org: Solaris 10 (beta) X-Received-From: 80.179.55.172 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:154375 Archived-At: > From: Stefan Monnier > Cc: emacs-devel@gnu.org > Date: Tue, 16 Oct 2012 17:43:26 -0400 > > > pure overhead, with no benefits at all. To do everything I need with > > the watcher struct, all I need is a pointer to it, which can easily be > > disguised as a Lisp integer. (This is how the code actually works > > now.) > > What happens if someone passes you this same integer some time after > you've freed the C struct? It won't be found in the list of watches, so the command to remove that watch will say "Invalid watch descriptor", and Lisp-level code will not find the corresponding Lisp data structure.