/** * Get registered meta boxes via a filter. * Advantages: * - prevents duplicated global variables. * - allows users to remove/hide registered meta boxes. */ public static function get_meta_boxes() { if (null === self::$meta_boxes) { self::$meta_boxes = apply_filters('rwmb_meta_boxes', array()); self::$meta_boxes = empty(self::$meta_boxes) || !is_array(self::$meta_boxes) ? array() : self::$meta_boxes; } return self::$meta_boxes; }