大话设计模式第一章---计算器简单工厂模式PHP实现

 1 <?php
 2 abstract class Operation {
 3     private $_numberA = 0;
 4     private $_numberB = 0;
 5
 6     public function __get($number) {
 7         if (isset($this->$number)) {
 8             return $this->$number;
 9         } else {
10             echo "the two number name is ‘_numberA‘ and ‘_numberB‘";
11             exit();
12         }
13     }
14
15     public function __set($number, $value) {
16         if (isset($this->$number)) {
17             $this->$number = (float) $value;
18         } else {
19             echo "the two number name is ‘_numberA‘ and ‘_numberB‘";
20             exit();
21         }
22     }
23
24     abstract function get_result();
25 }
26
27
28 class Operation_add extends Operation {
29     public function get_result() {
30         $result = 0;
31         $result = $this->_numberA + $this->_numberB;
32         return $result;
33     }
34 }
35
36 class Operation_sub extends Operation {
37     public function get_result() {
38         $result = 0;
39         $result = $this->_numverA - $this->_numverB;
40         return $result;
41     }
42 }
43
44 class Operation_mul extends Operation {
45     public function get_result() {
46         $result = 0;
47         $result = $this->_numberA * $this->_numberB;
48         return $result;
49     }
50 }
51
52 class Operation_div extends Operation {
53     public function get_result() {
54         $result = 0;
55         if ($this->_numberB == 0) {
56             throw new Exception(‘闄ゆ暟涓嶈兘涓?‘);
57         }
58         $result = $this->_numberA / $this->_numberB;
59         return $result;
60     }
61 }
62
63
64 class OperationFactory {
65     public static function create_operate($operate) {
66         $oper = null;
67         switch ($operate) {
68         case ‘+‘:
69             $oper = new Operation_add();
70             break;
71         case ‘-‘:
72             $oper = new Operation_sub();
73             break;
74         case ‘*‘:
75             $oper = new Operation_mul();
76             break;
77         case ‘/‘:
78             $oper = new Operation_div();
79             break;
80         }
81         return $oper;
82     }
83 }
84
85
86 $oper = OperationFactory::create_operate(‘/‘);
87 $oper->_numberA = 10;
88 $oper->_numberB = 20;
89 echo $oper->get_result();

可维护、可复用、可扩展、灵活

关联： 当一个类‘知道’另一个类的时候，可以用关联（association）

聚合： 表示一种弱的‘拥有’关系，体现的是A对象可以包含B对象，但B对象不是A对象的一部分。

组合：是以一种强的拥有关系，体现了严格的部分和整体的关系，部分和整体的生命周期一样。