Index: modules/filter/filter.api.php
===================================================================
RCS file: /cvs/drupal/drupal/modules/filter/filter.api.php,v
retrieving revision 1.9
diff -u -r1.9 filter.api.php
--- modules/filter/filter.api.php	13 Aug 2009 19:53:19 -0000	1.9
+++ modules/filter/filter.api.php	20 Aug 2009 17:08:12 -0000
@@ -104,5 +104,20 @@
 }
 
 /**
+ * Perform alterations on filter definitions.
+ *
+ * @param $info
+ *   Array of informations on filters exposed by hook_filter_info()
+ *   implementations.
+ */
+function hook_filter_info_alter(&$info) {
+  // Replace the PHP evaluator process callback with an improved PHP evaluator provided
+  // by a module.
+  $info['php_code'] += array(
+      'process callback' => 'my_module_php_evaluator',
+  );
+}
+
+/**
  * @} End of "addtogroup hooks".
  */
Index: modules/filter/filter.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/filter/filter.module,v
retrieving revision 1.270
diff -u -r1.270 filter.module
--- modules/filter/filter.module	20 Aug 2009 10:56:33 -0000	1.270
+++ modules/filter/filter.module	20 Aug 2009 17:08:19 -0000
@@ -325,25 +325,29 @@
 }
 
 /**
- * Build a list of all filters.
+ * Return a list of all filters provided by modules.
  */
-function filter_list_all() {
-  $filters = array();
-
-  foreach (module_implements('filter_info') as $module) {
-    $function = $module . '_filter_info';
-    $info = $function('list');
-    if (isset($info) && is_array($info)) {
-      foreach ($info as $delta => $filter) {
-        $filters[$module . '/' . $delta] = (object)($filter + array(
-          'module' => $module,
-          'delta' => $delta,
-        ));
+function filter_get_filters() {
+  $filters = &drupal_static(__FUNCTION__);
+  
+  if (empty($filters)) {
+    foreach (module_implements('filter_info') as $module) {
+      $function = $module . '_filter_info';
+      $info = $function();
+      if (isset($info) && is_array($info)) {
+        foreach ($info as $delta => $filter) {
+          $filters[$module . '/' . $delta] = $filter + array(
+            'module' => $module,
+            'delta' => $delta,
+          );
+        }
       }
     }
-  }
+    
+    drupal_alter('filter_info', $filters);
 
-  uasort($filters, '_filter_list_cmp');
+    uasort($filters, '_filter_list_cmp');
+  }
 
   return $filters;
 }
@@ -352,7 +356,7 @@
  * Helper function for sorting the filter list by filter name.
  */
 function _filter_list_cmp($a, $b) {
-  return strcmp($a->name, $b->name);
+  return strcmp($a['name'], $b['name']);
 }
 
 /**
@@ -378,14 +382,14 @@
  */
 function filter_list_format($format) {
   static $filters = array();
+  $filter_info = filter_get_filters();
 
   if (!isset($filters[$format])) {
     $filters[$format] = array();
-    $result = db_query("SELECT * FROM {filter} WHERE format = :format ORDER BY weight, module, delta", array(':format' => (int) $format));
+    $result = db_query("SELECT module, delta, weight FROM {filter} WHERE format = :format ORDER BY weight, module, delta", array(':format' => (int) $format));
     foreach ($result as $filter) {
-      $info = module_invoke($filter->module, 'filter_info');
-      if (isset($info) && is_array($info) && isset($info[$filter->delta])) {
-        $filter->name = $info[$filter->delta]['name'];
+      if (isset($filter_info[$filter->module . '/' . $filter->delta])) {
+        $filter->name = $filter_info[$filter->module . '/' . $filter->delta]['name'];
         $filters[$format][$filter->module . '/' . $filter->delta] = $filter;
       }
     }
@@ -442,20 +446,19 @@
 
     // Get a complete list of filters, ordered properly.
     $filters = filter_list_format($format);
+    $filter_info = filter_get_filters();
 
     // Give filters the chance to escape HTML-like data such as code or formulas.
-    foreach ($filters as $filter) {
-      $filter_info = module_invoke($filter->module, 'filter_info');
-      if (isset($filter_info[$filter->delta]['prepare callback']) && drupal_function_exists($filter_info[$filter->delta]['prepare callback'])) {
-        $text = call_user_func($filter_info[$filter->delta]['prepare callback'], $text, $format, $langcode, $cache_id);
+    foreach ($filters as $id => $filter) {
+      if (isset($filter_info[$id]['prepare callback']) && drupal_function_exists($filter_info[$id]['prepare callback'])) {
+        $text = call_user_func($filter_info[$id]['prepare callback'], $text, $format, $langcode, $cache_id);
       }
     }
 
     // Perform filtering.
-    foreach ($filters as $filter) {
-      $filter_info = module_invoke($filter->module, 'filter_info');
-      if (isset($filter_info[$filter->delta]['process callback']) && drupal_function_exists($filter_info[$filter->delta]['process callback'])) {
-        $text = call_user_func($filter_info[$filter->delta]['process callback'], $text, $format, $langcode, $cache_id);
+    foreach ($filters as $id => $filter) {
+      if (isset($filter_info[$id]['process callback']) && drupal_function_exists($filter_info[$id]['process callback'])) {
+        $text = call_user_func($filter_info[$id]['process callback'], $text, $format, $langcode, $cache_id);
       }
     }
 
@@ -551,6 +554,7 @@
  * Helper function for fetching filter tips.
  */
 function _filter_tips($format, $long = FALSE) {
+  $filter_info = filter_get_filters();
   if ($format == -1) {
     $formats = filter_formats();
   }
@@ -565,9 +569,8 @@
 
     $tips[$format->name] = array();
     foreach ($filters as $id => $filter) {
-      $filter_info = module_invoke($filter->module, 'filter_info');
-      if (isset($filter_info[$filter->delta]['tips callback']) && drupal_function_exists($filter_info[$filter->delta]['tips callback'])) {
-        $tip = call_user_func($filter_info[$filter->delta]['tips callback'],$format->format, $long);
+      if (isset($filter_info[$id]['tips callback']) && drupal_function_exists($filter_info[$id]['tips callback'])) {
+        $tip = call_user_func($filter_info[$id]['tips callback'],$format->format, $long);
         $tips[$format->name][] = array('tip' => $tip, 'id' => $id);
       }
     }
Index: modules/filter/filter.admin.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/filter/filter.admin.inc,v
retrieving revision 1.32
diff -u -r1.32 filter.admin.inc
--- modules/filter/filter.admin.inc	15 Aug 2009 06:50:29 -0000	1.32
+++ modules/filter/filter.admin.inc	20 Aug 2009 17:08:12 -0000
@@ -143,7 +143,7 @@
     }
   }
   // Table with filters
-  $all = filter_list_all();
+  $filter_info = filter_get_filters();
   $enabled = filter_list_format($format->format);
 
   $form['filters'] = array('#type' => 'fieldset',
@@ -151,12 +151,11 @@
     '#description' => t('Choose the filters that will be used in this text format.'),
     '#tree' => TRUE,
   );
-  foreach ($all as $id => $filter) {
-    $filter_info = module_invoke($filter->module, 'filter_info');
+  foreach ($filter_info as $id => $filter) {
     $form['filters'][$id] = array('#type' => 'checkbox',
-      '#title' => $filter->name,
+      '#title' => $filter['name'],
       '#default_value' => isset($enabled[$id]),
-      '#description' => $filter_info[$filter->delta]['description'],
+      '#description' => $filter['description'],
     );
   }
   if (!empty($format->format)) {
@@ -349,11 +348,11 @@
  */
 function filter_admin_configure(&$form_state, $format) {
   $list = filter_list_format($format->format);
+  $filter_info = filter_get_filters();
   $form = array();
-  foreach ($list as $filter) {
-    $filter_info = module_invoke($filter->module, 'filter_info');
-    if (isset($filter_info[$filter->delta]['settings callback']) && drupal_function_exists($filter_info[$filter->delta]['settings callback'])) {
-      $form_module = call_user_func($filter_info[$filter->delta]['settings callback'], $format->format);
+  foreach ($list as $id => $filter) {
+    if (isset($filter_info[$id]['settings callback']) && drupal_function_exists($filter_info[$id]['settings callback'])) {
+      $form_module = call_user_func($filter_info[$id]['settings callback'], $format->format);
     }
     if (isset($form_module) && is_array($form_module)) {
       $form = array_merge($form, $form_module);