From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: ludo@gnu.org (Ludovic =?iso-8859-1?Q?Court=E8s?=) Newsgroups: gmane.lisp.guile.devel Subject: Re: SCM_BOOL_F == 0 and BDW-GC Date: Fri, 18 Sep 2009 00:28:43 +0200 Message-ID: <87hbv11a04.fsf@gnu.org> 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> NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Trace: ger.gmane.org 1253226573 2546 80.91.229.12 (17 Sep 2009 22:29:33 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 17 Sep 2009 22:29:33 +0000 (UTC) To: guile-devel@gnu.org Original-X-From: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Fri Sep 18 00:29:26 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 1MoPTi-0006g5-7Q for guile-devel@m.gmane.org; Fri, 18 Sep 2009 00:29:26 +0200 Original-Received: from localhost ([127.0.0.1]:46868 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MoPTh-0003FC-G0 for guile-devel@m.gmane.org; Thu, 17 Sep 2009 18:29:25 -0400 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1MoPTe-0003F5-DR for guile-devel@gnu.org; Thu, 17 Sep 2009 18:29:22 -0400 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1MoPTZ-0003E8-NI for guile-devel@gnu.org; Thu, 17 Sep 2009 18:29:21 -0400 Original-Received: from [199.232.76.173] (port=52098 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MoPTZ-0003E5-JH for guile-devel@gnu.org; Thu, 17 Sep 2009 18:29:17 -0400 Original-Received: from lo.gmane.org ([80.91.229.12]:55048) by monty-python.gnu.org with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1MoPTZ-000226-46 for guile-devel@gnu.org; Thu, 17 Sep 2009 18:29:17 -0400 Original-Received: from list by lo.gmane.org with local (Exim 4.50) id 1MoPTW-0006cp-KK for guile-devel@gnu.org; Fri, 18 Sep 2009 00:29:14 +0200 Original-Received: from 78.251.23.100 ([78.251.23.100]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Fri, 18 Sep 2009 00:29:14 +0200 Original-Received: from ludo by 78.251.23.100 with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Fri, 18 Sep 2009 00:29:14 +0200 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 33 Original-X-Complaints-To: usenet@ger.gmane.org X-Gmane-NNTP-Posting-Host: 78.251.23.100 X-URL: http://www.fdn.fr/~lcourtes/ X-Revolutionary-Date: Jour du =?iso-8859-1?Q?G=E9nie?= de =?iso-8859-1?Q?l?= =?iso-8859-1?Q?'Ann=E9e?= 217 de la =?iso-8859-1?Q?R=E9volution?= X-PGP-Key-ID: 0xEA52ECF4 X-PGP-Key: http://www.fdn.fr/~lcourtes/ludovic.asc X-PGP-Fingerprint: 821D 815D 902A 7EAB 5CEE D120 7FBA 3D4F EB1F 5364 X-OS: x86_64-unknown-linux-gnu User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux) Cancel-Lock: sha1:1pubt2vZyaMz/LY8oMoUv8dGAZA= X-detected-operating-system: by monty-python.gnu.org: GNU/Linux 2.6 (newer, 3) 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:9345 Archived-At: Hello, Neil Jerram writes: > ludo@gnu.org (Ludovic Courtès) writes: [...] >> Instead what's really needed is a special pointer-to-reclaimed-object >> value that can be distinguished from valid Scheme values since that >> value ends up in the car or cdr of weak pairs in hash table buckets. As >> such, SCM_PACK (NULL) was a good choice until now. > > 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. >> SCM_UNDEFINED == 0 would work fine because SCM_UNDEFINED is not a valid >> 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 ‘scm_fixup_weak_alist ()’ would still be needed. > SCM_UNDEFINED == 0 is sounding promising... Yeah. Sorry for the false hope about SCM_BOOL_F == 0. Thanks, Ludo’.