简单工厂模式lua实现

1. OperationFactory = {}
2.  
3. Operation = {}
4.  
5. function Operation:new(o)
6. o = o or {}
7. setmetatable(o,self)
8. self.__index = self
9. o.NumberA = 0
10. o.NumberB = 1
11. return o
12. end
13.  
14. OperationAdd = Operation:new()
15.  
16. OperationSub = Operation:new()
17.  
18. OperationMul = Operation:new()
19.  
20. OperationDiv = Operation:new()
21.  
22. function OperationAdd:GetResult()
23. if self.NumberA and self.NumberB then
24. return self.NumberA + self.NumberB;
25. else
26. return "error"
27. end
28. end
29.  
30.  
31. function OperationSub:GetResult()
32. if self.NumberA and self.NumberB then
33. return self.NumberA - self.NumberB;
34. else
35. return "error"
36. end
37. end
38.  
39.  
40. function OperationMul:GetResult()
41. if self.NumberA and self.NumberB then
42. return self.NumberA * self.NumberB;
43. else
44. return "error"
45. end
46. end
47.  
48.  
49. function OperationDiv:GetResult()
50. if self.NumberA and self.NumberB and self.NumberB~=0 then
51. return self.NumberA / self.NumberB;
52. else
53. return "error"
54. end
55. end
56.  
57.  
58.  
59. function OperationFactory : CreateOperation(oper)
60. if oper == "+" then
61. return OperationAdd:new()
62. elseif oper == "-" then
63. return OperationSub:new()
64. elseif oper == "*" then
65. return OperationMul:new()
66. elseif oper == "/" then
67. return OperationDiv:new()
68. else
69. end
70. end
71.  
72. Oper1 = OperationFactory:CreateOperation("+")
73. Oper1.NumberA = 10
74. Oper1.NumberB = 5
75. print(Oper1:GetResult())
76.  
77. Oper2 = OperationFactory:CreateOperation("-")
78. Oper2.NumberA = 10
79. Oper2.NumberB = 5
80. print(Oper2:GetResult())
81.  
82. Oper3 = OperationFactory:CreateOperation("*")
83. Oper3.NumberA = 10
84. Oper3.NumberB = 5
85. print(Oper3:GetResult())
86.  
87. Oper4 = OperationFactory:CreateOperation("/")
88. Oper4.NumberA = 10
89. Oper4.NumberB = 5
90. print(Oper4:GetResult())

输出结果：
15
5
50
2