/** * Set value binder to use * * @param PHPExcel_Cell_IValueBinder $binder * @throws PHPExcel_Exception */ public static function setValueBinder(PHPExcel_Cell_IValueBinder $binder = null) { if ($binder === null) { throw new PHPExcel_Exception("A PHPExcel_Cell_IValueBinder is required for PHPExcel to function correctly."); } self::$valueBinder = $binder; }