The implementation of a simple calculator for Factory mode

<?phpabstract class  operation{public $num 1;public $num 2;public function setNum1 ($num 1) {$this->num1 = $num 1;} Public Function setNum2 ($num 2) {$this->num2 = $num 2;} Public Function GetResult () {return null;}} Class Add extends Operation{public function GetResult () {return $this->num1+ $this->num2;}} Class Mul extends Operation{public function GetResult () {return $this->num1* $this->num2;}} Class Factory{public static function Setopratory ($type) {switch ($type) {case ' + ': return new Add (); Break;case ' * ': return New Mul (); Break;default:return null;break;}}} $cal = factory::setopratory (' * '), $cal->setnum1 (4), $cal->setnum2 (2), $result = $cal->getresult ();

　　

The implementation of a simple calculator for Factory mode