public function setDate($m = 8, $d = 2, $y = 1975)
    {
        if (is_numeric($y) && $y > 0 && $y < 3000) {
            $this->year = floor($y);
        }
        
        if (is_numeric($m) && $m >= 1 && $m <= 12) {
            $this->month = floor($m);
        }
        
        if (is_numeric($d) && $d >= 1 && $d <= 31) {
            $this->day = floor($d);
        }
        
        return $this;
    }