php策略模式简单示例分析【区别于工厂模式】

//实现一个简单的计算器interface MathOp{  public function calculation($num1,$num2);}//加法class MathAdd implements MathOp{  public function calculation($num1,$num2){    return $num1 + $num2;  }}//减法class MathSub implements MathOp{  public function calculation($num1,$num2){    return $num1 - $num2;  }}//乘法class MathMulti implements MathOp{  public function calculation($num1,$num2){    return $num1 * $num2;  }}//除法class MathDiv implements MathOp{  public function calculation($num1,$num2){    return $num1 / $num2;  }}class Op{  protected $op_class = null;  public function __construct($op_type){    $this->op_class = 'Math' . $op_type;  }  public function get_result($num1,$num2){    $cls = new $this->op_class;    return $cls->calculation($num1,$num2);  }}$obj = new Op('Add');echo $obj->get_result(6,2);//8$obj = new Op('Sub');echo $obj->get_result(6,5);//1$obj = new Op('Multi');echo $obj->get_result(6,2);//12$obj = new Op('Div');echo $obj->get_result(6,2);//3