public function toString($separator = null)
    {
        if (!is_null($separator)) {
            $this->_separator = $separator;
        }

        $this->_prepareData();
        return $this->__toString();
    }
public function toString($separator = null)
    {
        if (!is_null($separator)) {
            $this->_separator = $separator;
        }

        $this->_prepareData();
        return $this->__toString();
    }
public function toString ( $ separator = null ) { if ( ! is_null ( $ separator ) ) { $ this -> _separator = $ separator ; } $ this -> _prepareData ( ) ; return $ this -> __toString ( ) ; }
return object as string
each data value separated by coma

@param string $separator
@return string
return object as string each data value separated by coma