public function setPattern($pattern)
    {
        $this->_pattern = (string) $pattern;
        $status         = @preg_match($this->_pattern, "Test");

        if (false === $status) {
            // require_once 'Zend/Validate/Exception.php';
            throw new Zend_Validate_Exception("Internal error while using the pattern '$this->_pattern'");
        }

        return $this;
    }