再谈智能指针

 1 #include <iostream>
 2 #include <vector>
 3 using namespace std;
 4 
 5 
 6 template <typename T> class SmartPtr;
 7 
 8 template<typename T>
 9 class RefPtr
10 {
11     friend class SmartPtr<T>;
12 
13     RefPtr(T *pointer = NULL):t( pointer), count(1)
14     {
15     }
16 
17     ~RefPtr()
18     {
19         cout << "destructor delete refptr" <<endl;
20         delete t;
21     }
22 
23     T *t;
24     int count;
25 
26 };
27 
28 
29 template<typename T>
30 class SmartPtr
31 {
32     public:
33         SmartPtr( T* object): rp(new RefPtr<T>(object))
34         {
35         }
36 
37         SmartPtr(const SmartPtr& rhs):rp(rhs.rp)
38         {
39             ++rp->count;
40         }
41 
42         SmartPtr& operator=(const SmartPtr &rhs)
43         {
44             if(this == &rhs)
45                 return *this;
46             
47             --rp->count;
48             if (rp->count == 0)
49                 delete rp;
50             
51             rp = rhs.rp;
52             ++rp->count;
53     
54             return *this;
55         }
56 
57         ~SmartPtr()
58         {
59             --rp->count;
60             if (rp->count == 0)
61                 delete rp;
62         }
63 
64     private:
65         RefPtr<T> *rp;
66 };
67 
68 
69 int main()
70 {
71     
72     {
73         SmartPtr<int> s1(new int(10));
74         SmartPtr<int> s2(s1);
75     
76         SmartPtr<int> s3 (new int (20));
77         s3 = s1;
78     }
79 
80     cout << "operator v1" << endl;
81 
82     {
83         vector<SmartPtr<int> > v1;
84         v1.push_back(SmartPtr<int>(new int (10)));
85         v1.push_back(SmartPtr<int>(new int (10)));
86         v1.push_back(SmartPtr<int>(new int (10)));
87         v1.push_back(SmartPtr<int>(new int (10)));
88     }
89 
90     cout << "operator v1 end" << endl;
91 }