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.user Subject: Re: Passing C pointers through guile Date: Wed, 09 Jul 2008 21:54:59 +0200 Message-ID: <87tzeyx27g.fsf@gnu.org> References: NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: ger.gmane.org 1215633335 12187 80.91.229.12 (9 Jul 2008 19:55:35 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 9 Jul 2008 19:55:35 +0000 (UTC) To: guile-user@gnu.org Original-X-From: guile-user-bounces+guile-user=m.gmane.org@gnu.org Wed Jul 09 21:56:22 2008 Return-path: Envelope-to: guile-user@m.gmane.org Original-Received: from lists.gnu.org ([199.232.76.165]) by lo.gmane.org with esmtp (Exim 4.50) id 1KGfly-000888-TY for guile-user@m.gmane.org; Wed, 09 Jul 2008 21:56:19 +0200 Original-Received: from localhost ([127.0.0.1]:44672 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1KGfl6-0003QD-WA for guile-user@m.gmane.org; Wed, 09 Jul 2008 15:55:25 -0400 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1KGfl1-0003O7-Jn for guile-user@gnu.org; Wed, 09 Jul 2008 15:55:19 -0400 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1KGfkz-0003NL-MK for guile-user@gnu.org; Wed, 09 Jul 2008 15:55:18 -0400 Original-Received: from [199.232.76.173] (port=46445 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1KGfkz-0003NI-GC for guile-user@gnu.org; Wed, 09 Jul 2008 15:55:17 -0400 Original-Received: from main.gmane.org ([80.91.229.2]:41444 helo=ciao.gmane.org) by monty-python.gnu.org with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1KGfky-0003bv-Nr for guile-user@gnu.org; Wed, 09 Jul 2008 15:55:17 -0400 Original-Received: from list by ciao.gmane.org with local (Exim 4.43) id 1KGfko-000737-M7 for guile-user@gnu.org; Wed, 09 Jul 2008 19:55:06 +0000 Original-Received: from reverse-83.fdn.fr ([80.67.176.83]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 09 Jul 2008 19:55:06 +0000 Original-Received: from ludo by reverse-83.fdn.fr with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 09 Jul 2008 19:55:06 +0000 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 34 Original-X-Complaints-To: usenet@ger.gmane.org X-Gmane-NNTP-Posting-Host: reverse-83.fdn.fr X-URL: http://www.fdn.fr/~lcourtes/ X-Revolutionary-Date: 22 Messidor an 216 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: i686-pc-linux-gnu User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.2 (gnu/linux) Cancel-Lock: sha1:ZQ/VU8m1pjpgZvzCm8wDb+uWsuA= X-detected-kernel: by monty-python.gnu.org: Linux 2.6, seldom 2.4 (older, 4) X-BeenThere: guile-user@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: General Guile related discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: guile-user-bounces+guile-user=m.gmane.org@gnu.org Errors-To: guile-user-bounces+guile-user=m.gmane.org@gnu.org Xref: news.gmane.org gmane.lisp.guile.user:6635 Archived-At: Hi, "Kjetil S. Matheussen" writes: > On Wed, 9 Jul 2008, Greg Troxel wrote: >> Does C guarantee that pointers fit in unsigned long? > > I don't know. But in practice: Yes. That's usually the case but it's not guaranteed, which is why C99 provides `uintptr_t' in . > Sure, if you just do this now and then, SMOBs aren't a problem. > But that doesn't change the fact that all the functionality SMOB > provides is overkill when the only thing you need is to hold > a pointer. It's not overkill, it's exactly what you need: disjoint SMOB type, `free' and `mark' procedures. > For those who needs the full functionality of SMOB's, or need > the extra speed and memory advantages of SMOB's, they are free > to use SMOB's. If not, the functions scm_to/from_uintptr > can be used instead, which is a billion times easier to use. Not really: as mentioned on `guile-devel', you'll need to implement that functionality (disjoint type, garbage collection) on top of your integer. One advantage is that this can be done in Scheme (except for the `mark' procedure, but it's not always needed); the main drawback in the context of Guile is poor performance. Thanks, Ludovic.