C + + callback (CallBack) use method (in fact, is the class method pointer, I think your method is not easy to use, although the principle is correct)

The callback function is a very useful and important concept. When an event occurs, the system or other function automatically calls a function that you define. Callback functions are used in many situations in Windows programming, such as Hook callback functions: Mouseproc,getmsgproc and Enumwindows,drawstate callback functions, and many system-level callback procedures. In general, we use the callback function basically is in the C language style. This article describes a C + + Style callback object method. Implemented using template.

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2. Template < class class, TypeName ReturnType, typename Parameter >
4. Class Singularcallback
6. {
10. Public :
14. typedef returntype (Class::* Method) (Parameter);
18. Singularcallback (class* _class_instance, Method _method)
20. {
22. //Get object instance address, and call method address
24. Class_instance = _class_instance;
26. method = _method;
28. };
32. ReturnType operator () (Parameter Parameter)
34. {
36. //Call object method
38. return (Class_instance->*method) (parameter);
40. };
44. ReturnType Execute (Parameter Parameter)
46. {
48. //Call object method
50. return operator () (parameter);
52. };
58. Private:
62. Class* class_instance;
64. Method method;
68. };

Example:

The following is a two class implementation.

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2. Class A
4. {
8. Public :
12. void output ()
14. {
16. Std::cout << "I am class A:D" << Std::endl;
18. };
22. };
26. Class B
28. {
32. Public :
36. BOOL MethodB (a A)
38. {
40. A.output ();
42. return true;
44. }
48. };

Examples of various invocations of Singularcallback:

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2. A;
4. b b;
8. singularcallback< B,bool,a >* CB;
10. CB = New singularcallback< B,bool,a > (&B,&B::METHODB);
14. if ((*CB) (a))
16. {
18. Std::cout << "CallBack fired successfully!" << Std::endl;
20. }
22. Else
24. {
26. Std::cout << "CallBack fired unsuccessfully!" << Std::endl;
28. }

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2. A;
4. b b;
8. singularcallback< B,bool,a >* CB;
10. CB = New singularcallback< B,bool,a > (&B,&B::METHODB);
14. if (Cb->execute (a))
16. {
18. Std::cout << "CallBack fired successfully!" << Std::endl;
20. }
22. Else
24. {
26. Std::cout << "CallBack fired unsuccessfully!" << Std::endl;
28. }

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1. A;
2. b b;
3. singularcallback< B,bool,a >CB (&B,&B::METHODB);
5. if (CB (a))
6. {
7. Std::cout << "CallBack fired successfully!" << Std::endl;
8. }
9. Else
10. {
11. Std::cout << "CallBack fired unsuccessfully!" << Std::endl;
12. }

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2. Class AClass
4. {
6. Public :
10. AClass (unsigned int _id): ID (_id) {};
12. ~aclass () {};
16. bool Amethod (std::string str)
18. {
20. Std::cout << "aclass[" << ID << "]:" << str << Std::endl;
22. return true;
24. };
28. Private:
32. unsigned int id;
36. };
42. typedef singularcallback < AClass, bool, std::string > Acallback;
48. int main ()
50. {
54. Std::vector < acallback > callback_list;
58. AClass A1 (1);
60. AClass A2 (2);
62. AClass A3 (3);
66. Callback_list.push_back (Acallback (&A1, &aclass::amethod));
68. Callback_list.push_back (Acallback (&A2, &aclass::amethod));
70. Callback_list.push_back (Acallback (&A3, &aclass::amethod));
74. For (unsigned int i = 0; i < callback_list.size (); i++)
76. {
78. Callback_list[i] ("abc");
80. }
84. For (unsigned int i = 0; i < callback_list.size (); i++)
86. {
88. Callback_list[i].execute ("abc");
90. }
94. return true;
98. }

Reference:

C + + Callback solution

Copyright NOTICE: This article for Bo Master original article, without Bo Master permission not reproduced. 4347329 such as the method of calling an unknown class object in the event-handling thread class, the thread object is only responsible for running the processing method when it is useful. You can download kylib:http://download.csdn.net/source/1538376 and use a lot of event method pointers in the Kylib class library, so you can refer to learning. Actually is the class method pointer, I think your method is not easy to use, although the principle is correct.
Can you take a look at my &lt; how to use the member method pointers of a class? &gt;: http://blog.csdn.net/kyee/archive/2009/03/20/4009735.aspx

C + + callback (CallBack) use method (in fact, is the class method pointer, I think your method is not easy to use, although the principle is correct)