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: Sat, 05 Jul 2008 18:59:26 +0200 Message-ID: <87d4lsxo5t.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 1215277193 29440 80.91.229.12 (5 Jul 2008 16:59:53 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sat, 5 Jul 2008 16:59:53 +0000 (UTC) To: guile-user@gnu.org Original-X-From: guile-user-bounces+guile-user=m.gmane.org@gnu.org Sat Jul 05 19:00:40 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 1KFB7j-0002Cf-7q for guile-user@m.gmane.org; Sat, 05 Jul 2008 19:00:35 +0200 Original-Received: from localhost ([127.0.0.1]:42906 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1KFB6s-0004Yd-CL for guile-user@m.gmane.org; Sat, 05 Jul 2008 12:59:42 -0400 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1KFB6n-0004Tt-Gw for guile-user@gnu.org; Sat, 05 Jul 2008 12:59:37 -0400 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1KFB6l-0004Q3-Ss for guile-user@gnu.org; Sat, 05 Jul 2008 12:59:37 -0400 Original-Received: from [199.232.76.173] (port=42503 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1KFB6l-0004Pt-P1 for guile-user@gnu.org; Sat, 05 Jul 2008 12:59:35 -0400 Original-Received: from main.gmane.org ([80.91.229.2]:42309 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 1KFB6l-0006Ua-8n for guile-user@gnu.org; Sat, 05 Jul 2008 12:59:35 -0400 Original-Received: from list by ciao.gmane.org with local (Exim 4.43) id 1KFB6j-0001Ac-At for guile-user@gnu.org; Sat, 05 Jul 2008 16:59:33 +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 ; Sat, 05 Jul 2008 16:59:33 +0000 Original-Received: from ludo by reverse-83.fdn.fr with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Sat, 05 Jul 2008 16:59:33 +0000 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 24 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: 18 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:NVnf/TcTDd3WwJW727XpdM513M8= 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:6627 Archived-At: Hi, "Maciek Godek" writes: > is there any portable and recommended way for passing C pointers around > in guile environment? > I think of something like scm_to_ptr (analogous to scm_to_int etc.). > Certainly such a value would be completely useless for the interpreter. > One can achieve simillar functionality using the aforementioned > scm_to_int (keeping track on the word length of the build target), > but it seems rather unnatural. If the goal is to make a C object pointed to by some pointer available to Scheme functions, the recommended (and simplest) way is to use a "SMOB" (see the manual for details). In practice, SMOBs incur some storage overhead because they hold 4 machines words, while you may only need one. Another possibility is to use a "uo" field in a struct: it allows you to have a struct field holding a machine word inaccessible to Scheme functions (see the "Vtables" node of the manual). Hope this helps, Ludovic.