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: packed structures usefulness Date: Fri, 02 Nov 2007 11:42:02 +0100 Message-ID: <87mytxkjyd.fsf@chbouib.org> References: NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: ger.gmane.org 1194000343 29446 80.91.229.12 (2 Nov 2007 10:45:43 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 2 Nov 2007 10:45:43 +0000 (UTC) To: guile-user@gnu.org Original-X-From: guile-user-bounces+guile-user=m.gmane.org@gnu.org Fri Nov 02 11:45:46 2007 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 1Inu1u-0001V7-Tl for guile-user@m.gmane.org; Fri, 02 Nov 2007 11:45:35 +0100 Original-Received: from localhost ([127.0.0.1] helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Inu1l-0001KO-0r for guile-user@m.gmane.org; Fri, 02 Nov 2007 06:45:25 -0400 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1Inu1b-0001AE-MT for guile-user@gnu.org; Fri, 02 Nov 2007 06:45:15 -0400 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1Inu1a-00017U-E9 for guile-user@gnu.org; Fri, 02 Nov 2007 06:45:14 -0400 Original-Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Inu1a-00017F-9z for guile-user@gnu.org; Fri, 02 Nov 2007 06:45:14 -0400 Original-Received: from main.gmane.org ([80.91.229.2] 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 1Inu1Z-0005Kp-EA for guile-user@gnu.org; Fri, 02 Nov 2007 06:45:13 -0400 Original-Received: from root by ciao.gmane.org with local (Exim 4.43) id 1Inu1O-0002r9-Fk for guile-user@gnu.org; Fri, 02 Nov 2007 10:45:02 +0000 Original-Received: from adh419.fdn.fr ([80.67.176.9]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Fri, 02 Nov 2007 10:45:02 +0000 Original-Received: from ludo by adh419.fdn.fr with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Fri, 02 Nov 2007 10:45:02 +0000 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 47 Original-X-Complaints-To: usenet@ger.gmane.org X-Gmane-NNTP-Posting-Host: adh419.fdn.fr X-URL: http://www.laas.fr/~lcourtes/ X-PGP-Key-ID: 0xEB1F5364 X-PGP-Key: http://www.laas.fr/~lcourtes/ludovic.asc X-PGP-Fingerprint: 821D 815D 902A 7EAB 5CEE D120 7FBA 3D4F EB1F 5364 X-OS: i486-pc-linux-gnu User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.1 (gnu/linux) Cancel-Lock: sha1:7Nlux8AtMENB/2qCRANXqYHXJqg= 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:6254 Archived-At: Hi, "Marco Maggi" writes: > I am in the position to add, with relatively > little effort, a module to GEE to handle > packed data structures. This means that, > as example of a still unimplemented API, doing: > > (define *triplet* > (make-gstruct-type '((one . int) > (two . double) > (three . (int64 . 3))))) > > (define S (make-gstruct *triplet*)) > > (set! (one S) 123) > (set! (two S) 1.2) > (set! (three S 2) 44) > > one can define a SMOB whose internal > representation is equivalent to the C language > type: > > struct triplet { > int one; > double two; > int64_t three[3]; > }; > > and then access its fields. > > Remembering that, IMHO, there is no way to > mimic the C structure fields alignment from a > Scheme level inteface, I wonder if such a module > would be useful or not. I'm not convinced. :-) Most "modern" C libraries use opaque types, typically pointers to structs, so you rarely get to access the fields directly. (BTW, note that Guile's structs have a specified C layout in terms of `SCM' fields, though.) Thanks, Ludovic. _______________________________________________ Guile-user mailing list Guile-user@gnu.org http://lists.gnu.org/mailman/listinfo/guile-user