module_implements

Determine which modules are implementing a hook.

Parameters

$hook: The name of the hook (e.g. "help" or "menu").

$sort: By default, modules are ordered by weight and filename, settings this option to TRUE, module list will be ordered by module name.

Return value

An array with the names of the modules which are implementing this hook.

See also

module_implements_write_cache()

Related topics

Hooks

Allow modules to interact with the Drupal core.

56 calls to module_implements()

5 string references to 'module_implements'

File

core/includes/module.inc, line 671

API for loading and interacting with Drupal modules.

Code

function module_implements($hook, $sort = FALSE) {
  // Use the advanced drupal_static() pattern, since this is called very often.
  static $drupal_static_fast;
  if (!isset($drupal_static_fast)) {
    $drupal_static_fast['implementations'] = &drupal_static(__FUNCTION__);
  }
  $implementations = &$drupal_static_fast['implementations'];

  // Fetch implementations from cache.
  if (empty($implementations)) {
    $implementations = cache('bootstrap')->get('module_implements');
    if ($implementations === FALSE) {
      $implementations = array();
    }
    else {
      $implementations = $implementations->data;
    }
  }

  if (!isset($implementations[$hook])) {
    // The hook is not cached, so ensure that whether or not it has
    // implementations, that the cache is updated at the end of the request.
    $implementations['#write_cache'] = TRUE;
    $hook_info = module_hook_info();
    $implementations[$hook] = array();
    $list = module_list(FALSE, FALSE, $sort);
    foreach ($list as $module) {
      $include_file = isset($hook_info[$hook]['group']) && module_load_include('inc', $module, $module . '.' . $hook_info[$hook]['group']);
      // Since module_hook() may needlessly try to load the include file again,
      // function_exists() is used directly here.
      if (function_exists($module . '_' . $hook)) {
        $implementations[$hook][$module] = $include_file ? $hook_info[$hook]['group'] : FALSE;
      }
    }
    // 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 => $group) {
      // If this hook implementation is stored in a lazy-loaded file, so include
      // that file first.
      if ($group) {
        module_load_include('inc', $module, "$module.$group");
      }
      // It is possible that a module removed a hook implementation without the
      // implementations cache being rebuilt yet, so we check whether the
      // function exists on each request to avoid undefined function errors.
      // Since module_hook() may needlessly try to load the include file again,
      // function_exists() is used directly here.
      if (!function_exists($module . '_' . $hook)) {
        // Clear out the stale implementation from the cache and force a cache
        // refresh to forget about no longer existing hook implementations.
        unset($implementations[$hook][$module]);
        $implementations['#write_cache'] = TRUE;
      }
    }
  }

  return array_keys($implementations[$hook]);
}