public static function getInstance() { if (is_null(self::$instance)) { $prefs = Preferences::getInstance(); if (!$prefs) { die_error('get Preferences failed', __FILE__, __LINE__); } $enabled_modules = $prefs->get('general', 'module_enable'); if (!in_array('SessionManagement', $enabled_modules)) { die_error('SessionManagement module must be enabled', __FILE__, __LINE__); } $SessionManagement_module_name = 'SessionManagement_' . $prefs->get('SessionManagement', 'enable'); self::$instance = new $SessionManagement_module_name(); } return self::$instance; }