From mboxrd@z Thu Jan 1 00:00:00 1970 Path: main.gmane.org!not-for-mail From: Rob Browning Newsgroups: gmane.lisp.guile.devel Subject: Re: The load path Date: Sun, 07 Nov 2004 15:16:50 -0600 Message-ID: <87hdo1e4vx.fsf@trouble.defaultvalue.org> References: <1097949129.4178.31.camel@localhost> <418C126D.5010802@ossau.uklinux.net> <87u0s3r30n.fsf@trouble.defaultvalue.org> <418D0EAE.40703@ossau.uklinux.net> <87wtwyk70v.fsf@trouble.defaultvalue.org> <418E6D90.5060705@ossau.uklinux.net> NNTP-Posting-Host: deer.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: sea.gmane.org 1099862279 17584 80.91.229.6 (7 Nov 2004 21:17:59 GMT) X-Complaints-To: usenet@sea.gmane.org NNTP-Posting-Date: Sun, 7 Nov 2004 21:17:59 +0000 (UTC) Cc: Marius Vollmer , guile-devel , Greg Troxel Original-X-From: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Sun Nov 07 22:17:43 2004 Return-path: Original-Received: from lists.gnu.org ([199.232.76.165]) by deer.gmane.org with esmtp (Exim 3.35 #1 (Debian)) id 1CQuPu-0000Fw-00 for ; Sun, 07 Nov 2004 22:17:43 +0100 Original-Received: from localhost ([127.0.0.1] helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.33) id 1CQuYE-0004Z2-JB for guile-devel@m.gmane.org; Sun, 07 Nov 2004 16:26:18 -0500 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.33) id 1CQuXg-0004Mt-My for guile-devel@gnu.org; Sun, 07 Nov 2004 16:25:44 -0500 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.33) id 1CQuXf-0004MK-QJ for guile-devel@gnu.org; Sun, 07 Nov 2004 16:25:44 -0500 Original-Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.33) id 1CQuXf-0004M5-M2 for guile-devel@gnu.org; Sun, 07 Nov 2004 16:25:43 -0500 Original-Received: from [66.93.216.237] (helo=defaultvalue.org) by monty-python.gnu.org with esmtp (Exim 4.34) id 1CQuP5-0005HZ-QI for guile-devel@gnu.org; Sun, 07 Nov 2004 16:16:52 -0500 Original-Received: from trouble.defaultvalue.org (omen.defaultvalue.org [192.168.1.1]) by defaultvalue.org (Postfix) with ESMTP id DE6F04123; Sun, 7 Nov 2004 15:16:49 -0600 (CST) Original-Received: by trouble.defaultvalue.org (Postfix, from userid 1000) id 2A8E841096; Sun, 7 Nov 2004 15:16:50 -0600 (CST) Original-To: Neil Jerram In-Reply-To: <418E6D90.5060705@ossau.uklinux.net> (Neil Jerram's message of "Sun, 07 Nov 2004 18:46:40 +0000") User-Agent: Gnus/5.1006 (Gnus v5.10.6) Emacs/21.3 (gnu/linux) 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: main.gmane.org gmane.lisp.guile.devel:4361 X-Report-Spam: http://spam.gmane.org/gmane.lisp.guile.devel:4361 Neil Jerram writes: > Agreed. I'd just note that versioning also has to cope with the case > where an add-on package A also provides an interface that further > packages {B, C, ...} may use, so there is also a requirement for > handling multiple installed versions of A, and for {B, C, ...} to be > able to get the version that they need. > > Unfortunately, I have no idea at this point how to solve such a > problem! One of the simplest ways I can think of to handle this (athough it's not all that pretty) is for packages to just put something like a "soname" in the module name. i.e. (use-modules (foo-1)). Then when the API changes incompatibly, the author just changes the module name to foo-2. This is already the best way to solve the dynamic linking problem, given the currently available dynamic linking facilities like libltdl. i.e. (dynamic-link "libfoo-2"). As far as use-modules is concerned, I can also imagine adding something fancier like (use-modules (foo #:version 4)), which might have more sophisticated semantics (like ld.so or something else). There's a further complication if you want to try to handle problems created when only some of the packages on a system have been upgraded and there are multiple levels of dependencies, A -> B -> D (-> means "depends on") A -> C -> D but the currently installed version of B depends on a different version of D than the currently installed version of C. This is also a problem in the shared library arena, and as far as I know the primary solution right now is to just say "don't do that". A distribution like Debian tries to make sure that the transition period where such situations exists is a short as possible and only happens in unstable (and maybe testing). In any case, I suspect all of this will be the subject of some future discussion. -- Rob Browning rlb @defaultvalue.org and @debian.org; previously @cs.utexas.edu GPG starting 2002-11-03 = 14DD 432F AE39 534D B592 F9A0 25C8 D377 8C7E 73A4 _______________________________________________ Guile-devel mailing list Guile-devel@gnu.org http://lists.gnu.org/mailman/listinfo/guile-devel