Android 智能指针学习一

Android5.1 中智能指针涉及的文件如下：

system/core/include/utils/RefBase.h

system/core/libutils/RefBase.cpp

system/core/include/utils/StrongPointer.h

在学习Android的智能指针时，对于模板的使用不太清楚，于是我将sp类精简了一下，大概看一下在赋值和初始化的时候的函数调用关系：

 #include <iostream>

 using namespace std;

 template<typename T>

 class sp {

 public:

     inline sp() {};

     sp(T* other);

     sp(const sp<T>& other);

     template<typename U> sp(U* other);

     template<typename U> sp(const sp<U>& other);

     ~sp();

     sp& operator = (T* other);

     sp& operator = (const sp<T>& other);

     template<typename U> sp& operator = (const sp<U>& other);

     template<typename U> sp& operator = (U* other);

 };

 template<typename T>

 sp<T>::sp(T* other) {

             cout << "enter sp(T* other) " << endl;

 }

 template<typename T>

 sp<T>::sp(const sp<T>& other) {

         cout << "enter sp(const sp<T>& other) " << endl;

 }

 template<typename T> template<typename U>

 sp<T>::sp(U* other) {

         cout << "enter sp(U *other) " << endl;

 }

 template<typename T> template<typename U>

 sp<T>::sp(const sp<U>& other) {

     cout << "sp(const sp<U& other>)" << endl;

 }

 template<typename T>

 sp<T>::~sp() {

 }

 template<typename T>

 sp<T>& sp<T>::operator =(T* other) {

     cout << "enter operator =(T* other) " << endl;

     return *this;

 }

 template<typename T>

 sp<T>& sp<T>::operator =(const sp<T>& other) {

     cout << "enter operator = (const sp<T>& other)" << endl;

     return *this;

 }

 template<typename T> template<typename U>

 sp<T>& sp<T>::operator =(const sp<U>& other) {

     cout << "operator = (const sp<U>& other)" << endl;

     return *this;

 }

 template<typename T> template<typename U>

 sp<T>& sp<T>::operator =(U* other) {

     cout << "operator = (U* other)" << endl;

     return *this;

 }

 class Peng{

 };

 class Dong {

 };

 int main(int argc, const char *argv[])

 {

     Peng *p = new Peng();

     Dong *d = new Dong();

     cout << "---- sp<Peng> q = p ----" << endl;

     sp<Peng> q = p;

     cout << "\n---- sp<Peng> r(p) ----" << endl;

     sp<Peng> r(p);

     cout << "\n---- sp<Peng> b(r) ----" << endl;

     sp<Peng> b(r);

     cout << "\n---- sp<Peng> t; ----" << endl;

     sp<Peng> t;

     cout << "\n---- t = p ----" << endl;

     t = p;

     cout << "\n---- sp<Peng> a; ----" << endl;

     sp<Peng> a;

     cout << "\n---- a = t ----" << endl;

     a = t;

     Dong *c = new Dong();

     cout << "\n---- sp<Dong> e = c ----" << endl;

     sp<Dong> e = c;

     cout << "\n---- a = e ----" << endl;

     a = e;

     cout << "\n---- a = c ----" << endl;

     a = c;

     cout << "\n---- sp<Dong> e1(e) ----" << endl;

     sp<Peng> e1(e);

     cout << endl << endl;

     return ;

 }

下面是在PC机上的运行结果：

pengdl@pengdl-HP:~/work/study/c++$ ./a.out

---- sp<Peng> q = p ----

enter sp(T* other) 

---- sp<Peng> r(p) ----

enter sp(T* other) 

---- sp<Peng> b(r) ----

enter sp(const sp<T>& other) 

---- sp<Peng> t; ----

---- t = p ----

enter operator =(T* other) 

---- sp<Peng> a; ----

---- a = t ----

enter operator = (const sp<T>& other)

---- sp<Dong> e = c ----

enter sp(T* other) 

---- a = e ----

operator = (const sp<U>& other)

---- a = c ----

operator = (U* other)

---- sp<Dong> e1(e) ----

sp(const sp<U& other>)

完。

巴特西

Android 智能指针学习一

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