public function setExpression(CronExpression $expression) {

        $this->minute = $expression->getExpression(0);
        $this->hour = $expression->getExpression(1);
        $this->day = $expression->getExpression(2);
        $this->month = $expression->getExpression(3);
        $this->weekday = $expression->getExpression(4);
        $this->year = $expression->getExpression(5);

        return $this;

    }