工厂方法模式lua实现

简单工厂就是生产整个计算器，而工厂方法只生产计算器的一部分；

原有的简单工厂可以生'+' '-' '*' '/' ;但是如果添加新的部件'%'，厂房就

需要扩充、修改很可以会影响原来部件的正常生产，这就违背了

开放封闭原则；而工厂方法则不存在这个问题；我新开一个工厂专门

生产'%'就可以了.

1. Factory = {}
2. Operation = {}
3. function Factory:new(o)
4. o = o or {}
5. setmetatable(o,self)
6. self.__index = self
7. return o;
8. end
9.  
10. function Operation:new(o)
11. o = o or {}
12. setmetatable(o,self)
13. self.__index = self
14. return o;
15. end
16.  
17.  
18.  
19. OperationAdd = Operation:new()
20.  
21. function OperationAdd:GetResult()
22. if self.NumberA and self.NumberB then
23. return self.NumberA + self.NumberB;
24. else
25. return "error"
26. end
27. end
28.  
29.  
30. FactoryAdd = Factory:new()
31.  
32. function FactoryAdd:CreateOperation()
33. return OperationAdd:new()
34. end
35.  
36. OperationSub = Operation:new()
37.  
38. function OperationSub:GetResult()
39. if self.NumberA and self.NumberB then
40. return self.NumberA - self.NumberB;
41. else
42. return "error"
43. end
44. end
45.  
46.  
47. FactorySub = Factory:new()
48.  
49. function FactorySub:CreateOperation()
50. return OperationSub:new()
51. end
52.  
53. OperationMul = Operation:new()
54.  
55. function OperationMul:GetResult()
56. if self.NumberA and self.NumberB then
57. return self.NumberA * self.NumberB;
58. else
59. return "error"
60. end
61. end
62.  
63.  
64. FactoryMul = Factory:new()
65.  
66. function FactoryMul:CreateOperation()
67. return OperationMul:new()
68. end
69.  
70. OperationDiv = Operation:new()
71.  
72. function OperationDiv:GetResult()
73. if self.NumberA and self.NumberB then
74. return self.NumberA / self.NumberB;
75. else
76. return "error"
77. end
78. end
79.  
80.  
81. FactoryDiv = Factory:new()
82.  
83. function FactoryDiv:CreateOperation()
84. return OperationDiv:new()
85. end
86.  
87.  
88.  
89. operAddFactory = FactoryAdd:new() --定义一个工厂对象
90.  
91. operAdd = operAddFactory:CreateOperation()
92.  
93. operAdd.NumberA = 10
94.  
95. operAdd.NumberB = 5
96.  
97. print("Add:"..operAdd:GetResult())
98.  
99. operSubFactory = FactorySub:new() --定义一个工厂对象
100.  
101. operSub = operSubFactory:CreateOperation()
102.  
103. operSub.NumberA = 10
104.  
105. operSub.NumberB = 5
106.  
107. print("Sub:"..operSub:GetResult())
108.  
109. operMulFactory = FactoryMul:new() --定义一个工厂对象
110.  
111. operMul = operMulFactory:CreateOperation()
112.  
113. operMul.NumberA = 10
114.  
115. operMul.NumberB = 5
116.  
117. print("Mul:"..operMul:GetResult())
118.  
119. operDivFactory = FactoryDiv:new() --定义一个工厂对象
120.  
121. operDiv = operDivFactory:CreateOperation()
122.  
123. operDiv.NumberA = 10
124.  
125. operDiv.NumberB = 5
126.  
127. print("Div:"..operDiv:GetResult())
128.  
129. --[[ **************新添加的'%'操作*************** ]]--
130.  
131. OperationMod = Operation:new()
132.  
133. function OperationMod:GetResult()
134. if self.NumberA and self.NumberB then
135. return self.NumberA % self.NumberB;
136. else
137. return "error"
138. end
139. end
140.  
141.  
142. FactoryMod = Factory:new()
143.  
144. function FactoryMod:CreateOperation()
145. return OperationMod:new()
146. end
147.  
148. operModFactory = FactoryMod:new() --定义一个工厂对象
149.  
150. operMod = operModFactory:CreateOperation()
151.  
152. operMod.NumberA = 10
153.  
154. operMod.NumberB = 5
155.  
156. print("Mod:"..operMod:GetResult())

输出结果：

Add:15
Sub:5
Mul:50
Div:2
Mod:0

这里有我的一篇简单工厂模式的博文。

简单工厂模式lua实现

如果用这篇博文里的简单工厂来添加'%',需要在

function OperationFactory : CreateOperation(oper)

中修改，添加一个'%'操作。这不符合开放封闭原则;

而用工厂方法，我们只需要扩展我们的程序，不需要做修改。

抽象工厂lua实现