Index: includes/common.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/common.inc,v
retrieving revision 1.1128
diff -u -p -r1.1128 common.inc
--- includes/common.inc	12 Mar 2010 14:20:32 -0000	1.1128
+++ includes/common.inc	14 Mar 2010 18:37:40 -0000
@@ -4535,86 +4535,6 @@ function drupal_system_listing($mask, $d
 }
 
 /**
- * Hands off alterable variables to type-specific *_alter implementations.
- *
- * This dispatch function hands off the passed in variables to type-specific
- * hook_TYPE_alter() implementations in modules. It ensures a consistent
- * interface for all altering operations.
- *
- * A maximum of 2 alterable arguments is supported. In case more arguments need
- * to be passed and alterable, modules provide additional variables assigned by
- * reference in the last $context argument:
- * @code
- *   $context = array(
- *     'alterable' => &$alterable,
- *     'unalterable' => $unalterable,
- *     'foo' => 'bar',
- *   );
- *   drupal_alter('mymodule_data', $alterable1, $alterable2, $context);
- * @endcode
- *
- * Note that objects are always passed by reference in PHP5. If it is absolutely
- * required that no implementation alters a passed object in $context, then an
- * object needs to be cloned:
- * @code
- *   $context = array(
- *     'unalterable_object' => clone $object,
- *   );
- *   drupal_alter('mymodule_data', $data, $context);
- * @endcode
- *
- * @param $type
- *   A string describing the data type of the alterable $data. 'form', 'links',
- *   'node_content', and so on are several examples.
- * @param &$data
- *   The primary data to be altered.
- * @param &$context1
- *   (optional) An additional variable that is passed by reference.
- * @param &$context2
- *   (optional) An additional variable that is passed by reference. If more
- *   context needs to be provided to implementations, then this should be an
- *   keyed array as described above.
- */
-function drupal_alter($type, &$data, &$context1 = NULL, &$context2 = NULL) {
-  // Use the advanced drupal_static() pattern, since this is called very often.
-  static $drupal_static_fast;
-  if (!isset($drupal_static_fast)) {
-    $drupal_static_fast['functions'] = &drupal_static(__FUNCTION__);
-  }
-  $functions = &$drupal_static_fast['functions'];
-
-  // Some alter hooks are invoked many times per page request, so statically
-  // cache the list of functions to call, and on subsequent calls, iterate
-  // through them quickly.
-  if (!isset($functions[$type])) {
-    $functions[$type] = array();
-    $hook = $type . '_alter';
-    foreach (module_implements($hook) as $module) {
-      $functions[$type][] = $module . '_' . $hook;
-    }
-    // Allow the theme to alter variables after the theme system has been
-    // initialized.
-    global $theme, $base_theme_info;
-    if (isset($theme)) {
-      $theme_keys = array();
-      foreach ($base_theme_info as $base) {
-        $theme_keys[] = $base->name;
-      }
-      $theme_keys[] = $theme;
-      foreach ($theme_keys as $theme_key) {
-        $function = $theme_key . '_' . $hook;
-        if (function_exists($function)) {
-          $functions[$type][] = $function;
-        }
-      }
-    }
-  }
-  foreach ($functions[$type] as $function) {
-    $function($data, $context1, $context2);
-  }
-}
-
-/**
  * Set the main page content value for later use.
  *
  * Given the nature of the Drupal page handling, this will be called once with
Index: includes/module.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/module.inc,v
retrieving revision 1.184
diff -u -p -r1.184 module.inc
--- includes/module.inc	3 Mar 2010 07:38:08 -0000	1.184
+++ includes/module.inc	14 Mar 2010 18:37:40 -0000
@@ -588,6 +588,11 @@ function module_implements($hook, $sort 
         $implementations['#write_cache'] = TRUE;
       }
     }
+    // Allow modules to change the weight of specific implementations but avoid
+    // an infinite loop.
+    if ($hook != 'module_implements_alter') {
+      drupal_alter('module_implements', $implementations[$hook], $hook);
+    }
   }
   else {
     foreach ($implementations[$hook] as $module => $group) {
@@ -741,3 +746,83 @@ function drupal_required_modules() {
 
   return $required;
 }
+
+/**
+ * Hands off alterable variables to type-specific *_alter implementations.
+ *
+ * This dispatch function hands off the passed in variables to type-specific
+ * hook_TYPE_alter() implementations in modules. It ensures a consistent
+ * interface for all altering operations.
+ *
+ * A maximum of 2 alterable arguments is supported. In case more arguments need
+ * to be passed and alterable, modules provide additional variables assigned by
+ * reference in the last $context argument:
+ * @code
+ *   $context = array(
+ *     'alterable' => &$alterable,
+ *     'unalterable' => $unalterable,
+ *     'foo' => 'bar',
+ *   );
+ *   drupal_alter('mymodule_data', $alterable1, $alterable2, $context);
+ * @endcode
+ *
+ * Note that objects are always passed by reference in PHP5. If it is absolutely
+ * required that no implementation alters a passed object in $context, then an
+ * object needs to be cloned:
+ * @code
+ *   $context = array(
+ *     'unalterable_object' => clone $object,
+ *   );
+ *   drupal_alter('mymodule_data', $data, $context);
+ * @endcode
+ *
+ * @param $type
+ *   A string describing the data type of the alterable $data. 'form', 'links',
+ *   'node_content', and so on are several examples.
+ * @param &$data
+ *   The primary data to be altered.
+ * @param &$context1
+ *   (optional) An additional variable that is passed by reference.
+ * @param &$context2
+ *   (optional) An additional variable that is passed by reference. If more
+ *   context needs to be provided to implementations, then this should be an
+ *   keyed array as described above.
+ */
+function drupal_alter($type, &$data, &$context1 = NULL, &$context2 = NULL) {
+  // Use the advanced drupal_static() pattern, since this is called very often.
+  static $drupal_static_fast;
+  if (!isset($drupal_static_fast)) {
+    $drupal_static_fast['functions'] = &drupal_static(__FUNCTION__);
+  }
+  $functions = &$drupal_static_fast['functions'];
+
+  // Some alter hooks are invoked many times per page request, so statically
+  // cache the list of functions to call, and on subsequent calls, iterate
+  // through them quickly.
+  if (!isset($functions[$type])) {
+    $functions[$type] = array();
+    $hook = $type . '_alter';
+    foreach (module_implements($hook) as $module) {
+      $functions[$type][] = $module . '_' . $hook;
+    }
+    // Allow the theme to alter variables after the theme system has been
+    // initialized.
+    global $theme, $base_theme_info;
+    if (isset($theme)) {
+      $theme_keys = array();
+      foreach ($base_theme_info as $base) {
+        $theme_keys[] = $base->name;
+      }
+      $theme_keys[] = $theme;
+      foreach ($theme_keys as $theme_key) {
+        $function = $theme_key . '_' . $hook;
+        if (function_exists($function)) {
+          $functions[$type][] = $function;
+        }
+      }
+    }
+  }
+  foreach ($functions[$type] as $function) {
+    $function($data, $context1, $context2);
+  }
+}
Index: modules/system/system.api.php
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.api.php,v
retrieving revision 1.142
diff -u -p -r1.142 system.api.php
--- modules/system/system.api.php	11 Mar 2010 21:23:06 -0000	1.142
+++ modules/system/system.api.php	14 Mar 2010 18:37:45 -0000
@@ -977,6 +977,32 @@ function hook_mail_alter(&$message) {
 }
 
 /**
+ * Alter the registry of modules implementing a hook.
+ *
+ * This hook is invoked during module_implements(). A module may implement this
+ * hook in order to reorder the implementing modules, which are otherwise
+ * ordered by the module's system weight.
+ *
+ * @param &$implementations
+ *   An array keyed by the module's name. The value of each item corresponds
+ *   to a $group, which is usually FALSE, unless the implementation is in a
+ *   file named $module.$group.inc.
+ * @param $hook
+ *   The name of the module hook being implemented.
+ */
+function hook_module_implements_alter(&$implementations, $hook) {
+  if ($hook == 'rdf_mapping') {
+    // Move my_module_rdf_mapping() to the end of the list. module_implements()
+    // iterates through $implementations with a foreach loop which PHP iterates
+    // in the order that the items were added, so to move an item to the end of
+    // the array, we remove it and then add it.
+    $group = $implementations['my_module'];
+    unset($implementations['my_module']);
+    $implementations['my_module'] = $group;
+  }
+}
+
+/**
  * Alter the information parsed from module and theme .info files
  *
  * This hook is invoked in _system_rebuild_module_data() and in