private function _serializeCallback( $callback )
    {
        $retVal = $callback;

        if ( is_array( $callback ) && 2 === count( $callback ) )
        {
            $retVal = get_class( $callback[ 0 ] ) . '/' . $callback[ 1 ];
        }

        return $retVal;
    }
private function _serializeCallback( $callback )
    {
        $retVal = $callback;

        if ( is_array( $callback ) && 2 === count( $callback ) )
        {
            $retVal = get_class( $callback[ 0 ] ) . '/' . $callback[ 1 ];
        }

        return $retVal;
    }
private function _serializeCallback ( $ callback ) { $ retVal = $ callback ; if ( is_array ( $ callback ) && 2 === count ( $ callback ) ) { $ retVal = get_class ( $ callback [ 0 ] ) . '/' . $ callback [ 1 ] ; } return $ retVal ; }
Helper method to serialize a callback.

@param mixed $callback the callback string or array

@return string the serialized callback
Helper method to serialize a callback .