php设计模式--策略模式（六）

<?php
//策略模式  做一个计算器
interface Math {
  public function calc($op1 ,$op2); 
}
  class MathAdd implements Math{
    public function calc($op1,$op2) {
      return $op1+$op2; 
    }
  }
  class MathSub implements Math{
    public function calc($op1,$op2) {
      return $op1-$op2 ; 
    }
  }
  class MathMul implements Math{
    public function calc($op1,$op2) {
      return $op1*$op2; 
    }
  }
/* 一般思路，根据传来0P ,制造不对对象,并且调用.
if($_ POST[ 'op']
*/
  class CMath {
    protected $calc = null ;
    public function  __construct($type){
      $calc = 'Math' . $type;
      $this->calc =new $calc();
    }
    public function calc($op1,$op2) {
      return $this->calc->calc($op1, $op2);
    }
  }
  //$type = $_POST['op']; 
  //$cmath = new CMath($type);
  //$cmath->calc($_POST['op1'],_POST['op2']);
  
  $type = 'add';
  $cmath = new CMath($type);
  echo $cmath->calc(3,5);