Index: includes/module.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/module.inc,v
retrieving revision 1.82
diff -u -F^f -r1.82 module.inc
--- includes/module.inc 20 Aug 2006 05:57:40 -0000      1.82
+++ includes/module.inc 22 Aug 2006 00:08:52 -0000
@@ -193,6 +193,27 @@ function module_disable($module) {
 }

 /**
+ * Updates system hook definitions.
+ */
+function module_update_hooks($module, $enable = 1) {
+  $hooks = call_user_func("$module_define_hooks");
+  if ($enable) {
+    foreach ($hooks as $hook) {
+      $implementations = variable_get($hook, array());
+      $implementations[$module] = $module;
+      variable_set($hook, $implementations);
+    }
+  }
+  elseif ($disable) {
+    foreach ($hooks as $hook) {
+      $implementations = variable_get($hook, array());
+      unset($implementations[$module]);
+      variable_set($hook, $implementations);
+    }
+  }
+}
+
+/**
  * @defgroup hooks Hooks
  * @{
  * Allow modules to interact with the Drupal core.
@@ -240,25 +261,11 @@ function module_hook($module, $hook) {
  *   An array with the names of the modules which are implementing this hook.
  */
 function module_implements($hook, $sort = FALSE) {
-  static $implementations;
-
-  if (!isset($implementations[$hook])) {
-    $implementations[$hook] = array();
-    $list = module_list(FALSE, TRUE, $sort);
-    foreach ($list as $module) {
-      if (module_hook($module, $hook)) {
-        $implementations[$hook][] = $module;
-      }
-    }
+  $modules = array_keys(variable_get("hook_$hook", array()));
+  if ($sort) {
+    sort($modules);
   }
-
-  // The explicit cast forces a copy to be made. This is needed because
-  // $implementations[$hook] is only a reference to an element of
-  // $implementations and if there are nested foreaches (due to nested node
-  // API calls, for example), they would both manipulate the same array's
-  // references, which causes some modules' hooks not to be called.
-  // See also http://www.zend.com/zend/art/ref-count.php.
-  return (array)$implementations[$hook];
+  return $modules;
 }

 /**