Design Pattern---simple factory

Simple Factory mode: The store---a lot of pastries, you need to build through the factory. The goal is to reduce the code by first writing a parent class, then having the subclass inherit the parent class, and then writing a factory class that invokes different subclasses depending on the switch.

When testing, call the factory class directly.

Directly on the code:

The following algorithm is an implementation of a calculator:

2. using System;
4. using System.Collections.Generic;
6. using System.Linq;
8. using System.Text;
10. ?
12. namespace Designdemo
14. {
16. ???? class Operation2
18. ???? {
20. ???????? Private double _numbera;
22. ???????? Private double _numberb;
24. ?
26. ???????? Public Double Numbera
28. ???????? {
30. ???????????? Get {return _numbera;}
32. ???????????? Set {_numbera = value;}
34. ????????}
36. ?
38. ???????? Public Double Numberb
40. ???????? {
42. ???????????? Get { return _numberb;}
44. ???????????? Set {_numberb = value;}
46. ????????}
48. ?
50. ???????? Public Virtual Double GetResult ()
52. ???????? {
54. ???????????? double result = 0d;
56. ???????????? return result;
58. ????????}
60. ????}
62. ?
64. ???? class Operationadd:operation2
66. ???? {
68. ???????? Public Override Double GetResult ()
70. ???????? {
72. ???????????? double result = 0;
74. ???????????? result = Numbera + Numberb;
76. ???????????? return result;
78. ????????}
80. ????}
82. ?
84. ???? class Operationsub:operation2
86. ???? {
88. ???????? Public Override Double GetResult ()
90. ???????? {
92. ???????????? double result = 0;
94. ???????????? result = Numbera-numberb;
96. ???????????? return result;
98. ????????}
100. ????}
102. ?
104. ???? class Operationmul:operation2
106. ???? {
108. ???????? Public Override Double GetResult ()
110. ???????? {
112. ???????????? double result = 0;
114. ???????????? result = Numbera * NUMBERB;
116. ???????????? return result;
118. ????????}
120. ????}
122. ?
124. ???? class Operationdiv:operation2
126. ???? {
128. ???????? Public Override Double GetResult ()
130. ???????? {
132. ???????????? double result = 0;
134. ???????????? if (Numberb = = 0)
136. ???????????? {
138. ???????????????? Throw New Exception (" divisor cannot be 0");
140. ????????????}
142. ???????????? result = Numbera/numberb;
144. ???????????? return result;
146. ????????}
148. ????}
150. ?
152. ?
154. ???? /************************************************************************/
156. ???? /* Build a simple factory model: reduce coupling, encapsulate changing things into classes */
158. ???? /************************************************************************/
160. ?
162. ???? class Operationfactory
164. ???? {
166. ???????? Public Static Operation2 createoperate (string operate)
168. ???????? {
170. ???????????? Operation2 per = null;
172. ???????????? Switch (operate)
174. ???????????? {
176. ???????????????? Case "+":
178. ???????????????????? per = new operationadd ();
180. ???????????????????? break;
182. ???????????????? Case "-":
184. ???????????????????? per = new operationsub ();
186. ???????????????????? break;
188. ???????????????? Case "*":
190. ???????????????????? per = new Operationmul ();
192. ???????????????????? break;
194. ???????????????? Case "/":
196. ???????????????????? per = new operationdiv ();
198. ???????????????????? break;
200. ????????????}
202. ???????????? return per;
204. ????????}
206. ????}
208. }

Design Pattern---simple factory