Index: openacs-4/packages/xowiki/tcl/xowiki-callback-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/xowiki/tcl/xowiki-callback-procs.tcl,v
diff -u -r1.43 -r1.44
--- openacs-4/packages/xowiki/tcl/xowiki-callback-procs.tcl	25 Aug 2008 11:33:56 -0000	1.43
+++ openacs-4/packages/xowiki/tcl/xowiki-callback-procs.tcl	1 Sep 2008 21:15:35 -0000	1.44
@@ -27,7 +27,39 @@
     }
   }
 
+  ad_proc -public ::xowiki::before-uninstantiate {
+    {-package_id:required}
+  } {
+    Callback to be called whenever a package instance is deleted.
+    
+    @author Gustaf Neumann
+  } {
+    ns_log notice "Executing before-uninstantiate"
+    ::xowiki::delete_gc_messages -package_id $package_id
+    ns_log notice "          before-uninstantiate DONE"
+  }
 
+
+  ad_proc -public ::xowiki::delete_gc_messages {
+    {-package_id:required}
+  } {
+    Deletes the messages of general comments to allow to
+    uninstantiate the package without violating constraints.
+    
+    @author Gustaf Neumann
+  } {
+    set comment_ids [db_list get_comments "
+      select g.comment_id
+      from general_comments g, cr_items i,acs_objects o
+      where i.item_id = g.object_id
+      and o.object_id = i.item_id
+      and o.package_id = $package_id"]
+    foreach comment_id $comment_ids {
+      ::xo::db::sql::acs_message delete -message_id $comment_id
+    }
+  }
+
+
   #
   # upgrade logic
   #