From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Neil Jerram Newsgroups: gmane.lisp.guile.devel Subject: Re: SCM_BOOL_F == 0 and BDW-GC Date: Fri, 18 Sep 2009 21:51:19 +0100 Message-ID: <87zl8sc6yg.fsf@ossau.uklinux.net> References: <87k52uvhnt.fsf@arudy.ossau.uklinux.net> <20090702142823.GA1401@fibril.netris.org> <877hyqk8bx.fsf@arudy.ossau.uklinux.net> <20090703153218.GA1382@fibril.netris.org> <20090705024135.GA2363@fibril.netris.org> <20090707111406.GA1388@fibril.netris.org> <87iqg5y2o8.fsf@arudy.ossau.uklinux.net> <87zl9fps1m.fsf_-_@gnu.org> <87iqfhgrjy.fsf@ossau.uklinux.net> <87hbv11a04.fsf@gnu.org> NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=gb2312 Content-Transfer-Encoding: quoted-printable X-Trace: ger.gmane.org 1253307104 20251 80.91.229.12 (18 Sep 2009 20:51:44 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 18 Sep 2009 20:51:44 +0000 (UTC) Cc: guile-devel@gnu.org To: ludo@gnu.org (Ludovic =?iso-8859-1?Q?Court=E8s?=) Original-X-From: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Fri Sep 18 22:51:37 2009 Return-path: Envelope-to: guile-devel@m.gmane.org Original-Received: from lists.gnu.org ([199.232.76.165]) by lo.gmane.org with esmtp (Exim 4.50) id 1MokQb-0006sb-0V for guile-devel@m.gmane.org; Fri, 18 Sep 2009 22:51:37 +0200 Original-Received: from localhost ([127.0.0.1]:45746 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MokQa-0001vJ-LF for guile-devel@m.gmane.org; Fri, 18 Sep 2009 16:51:36 -0400 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1MokQZ-0001vE-0r for guile-devel@gnu.org; Fri, 18 Sep 2009 16:51:35 -0400 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1MokQS-0001v2-T6 for guile-devel@gnu.org; Fri, 18 Sep 2009 16:51:33 -0400 Original-Received: from [199.232.76.173] (port=44059 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MokQS-0001uz-Mj for guile-devel@gnu.org; Fri, 18 Sep 2009 16:51:28 -0400 Original-Received: from mail3.uklinux.net ([80.84.72.33]:34139) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1MokQK-0005Z7-Vb; Fri, 18 Sep 2009 16:51:21 -0400 Original-Received: from arudy (host86-147-112-99.range86-147.btcentralplus.com [86.147.112.99]) by mail3.uklinux.net (Postfix) with ESMTP id 68BF61F661A; Fri, 18 Sep 2009 21:51:20 +0100 (BST) Original-Received: from arudy (arudy [127.0.0.1]) by arudy (Postfix) with ESMTP id CE05A38023; Fri, 18 Sep 2009 21:51:19 +0100 (BST) In-Reply-To: <87hbv11a04.fsf@gnu.org> ("Ludovic =?iso-8859-1?Q?Court=E8s?= =?iso-8859-1?Q?=22's?= message of "Fri, 18 Sep 2009 00:28:43 +0200") User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux) X-detected-operating-system: by monty-python.gnu.org: GNU/Linux 2.4-2.6 X-BeenThere: guile-devel@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "Developers list for Guile, the GNU extensibility library" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Errors-To: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.lisp.guile.devel:9353 Archived-At: ludo@gnu.org (Ludovic Court=A8=A8s) writes: > Hello, > > Neil Jerram writes: >> >> Here I'm confused again. I thought we now had no choice about the >> pointer-to-reclaimed-object value, because BDW-GC always uses NULL. > > True. So, what I meant is that ((SCM) NULL) must be distinguishable > from valid Scheme values. OK. >>> SCM_UNDEFINED =3D=3D 0 would work fine because SCM_UNDEFINED is not a v= alid >>> Scheme value, but it wouldn't change the implementation. >> >> I'm afraid I don't understand "but it wouldn't change the >> implementation". > > Ugly stuff like =A1=AEscm_fixup_weak_alist ()=A1=AF would still be needed. Thanks, I understand now. scm_fixup_weak_alist looks OK to me. Surely we must have had something like that with Guile GC too? (Except that it was probably mixed up with the GC'ing code, and so was even uglier!) >> SCM_UNDEFINED =3D=3D 0 is sounding promising... > > Yeah. Sorry for the false hope about SCM_BOOL_F =3D=3D 0. So are you going to try out SCM_UNDEFINED =3D=3D 0 ? Neil