Proxy pattern (C ++ source code)

Proxy mode removes the real operations of the original class from the caller's perspective, and may also add operations that the caller is not aware, however, from the perspective of the class designer, this does not affect the caller's use of the original class function. To protect a class, the caller generates a new class and does not dare to say that the idea is very correct, at least I feel a little uncomfortable when I turn a bend to achieve my goal. Maybe the real power of the proxy mode is the dynamic proxy method derived from this.

1. // Proxyparenter. cpp: defines the entry point for the console application.
2. //
4. // The proxy mode is the object structure mode, and the operation target is a class object.
5. // The following is a classic and simplified example:
7. # Include "stdafx. H"
8. # Include <iostream>
10. Using namespace STD;
12. // Abstract role
13. Class isubject
14. {
15. Public:
16. Isubject ()
17. {
18. }
20. Virtual ~ Isubject ()
21. {
22. }
23. Public:
24. Virtual void request () = 0;
25. };
27. // Real role: implements the subject request () method.
28. Class csubject: Public isubject
29. {
30. Public:
31. Csubject ()
32. {
33. }
34. Virtual ~ Csubject ()
35. {
36. }
38. Public:
39. Virtual void request ()
40. {
41. Cout <"csubject: Request ()" <Endl;
42. }
43. };
45. // Proxy role
46. Class cproxysubject: Public isubject
47. {
48. Public:
49. Cproxysubject (int nid)
50. {
51. This-> m_nid = NID;
52. }
54. Virtual ~ Cproxysubject ()
55. {
56. }
58. Public:
59. Virtual void request ()
60. {
61. If (! This-> prerequest (this-> m_nid ))
62. {
63. Cout <"request reject! "<Endl;
64. Return;
65. }
67. This-> m_objsub.request ();
69. This-> afterrequest ();
70. }
72. Void setid (int nid)
73. {
74. This-> m_nid = NID;
75. }
77. Int GETID ()
78. {
79. Return this-> m_nid;
80. }
82. PRIVATE:
83. Bool prerequest (int nid)
84. {
85. If (NID> 0) & (NID <= 100 ))
86. {
87. Return true;
88. }
90. Return false;
91. }
93. Void afterrequest ()
94. {
95. Cout <"after do request! "<Endl;
96. }
98. PRIVATE:
99. Csubject m_objsub;
100. Int m_nid;
101. };
103. Int main ()
104. {
105. Isubject * pobj = NULL;
106. Int nid = 0;
108. Cout <"Please input your ID:" <Endl;
109. Cin> NID;
111. Pobj = new cproxysubject (NID );
113. If (null! = Pobj)
114. {
115. Pobj-> request ();
116. }
118. // Clear
119. If (null! = Pobj)
120. {
121. Delete pobj;
122. Pobj = NULL;
123. }
124. }