<?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