php之简单工厂模式

<?php
/**
 * Created by PhpStorm.
 * User: 小狗蛋儿
 * Date: 2017/11/13
 * Time: 22:21
 */

abstract class Operation{
    public  $num1;
    public  $num2;

     abstract function GetResult($num1,$num2);

}

class OperationAdd extends Operation{
     public  function GetResult($num1,$num2)
     {
         $result=0;
         $result=$num1+$num2;
         return $result;
     }
}

class Factory{

     public static function CreateOperatop($operator){

//           switch ($operator){
//               case "+":
//                  return new OperationAdd();
//                  break;
//
//           }
         if ($operator=="+") {
             $name = "add"; //
         }
         $operatorObj='Operation'.ucfirst($name);
         return new $operatorObj();

     }
}

//$test=Factory::CreateOperatop("+");
//$result=$test->GetResult(10,10);
//echo $result;

$test=Factory::CreateOperatop("+");
$result=$test->GetResult(10,10);
echo $result;

整体意思就是：怎么new  实例化才 减少修改