C++之模板（四）

1、用模板实现单例模式

SIngleton.h

#include "iostream"
using namespace std;template <typename T>
class Singleton
{
public:static T& GetInstance(){Init();return *instance_;}private:static void Init(){if (instance_ == 0){instance_ = new T;atexit(Destroy);  // 注册函数，当程序结束的时候会自动调用这个函数}}static void Destroy(){delete instance_;}Singleton(const Singleton& other);Singleton& operator=(const Singleton& other);Singleton(){}~Singleton(){}static T* instance_;
};template <typename T>
T* Singleton<T>::instance_ = 0;

main.cpp

#include <iostream>
#include "Singleton.h"class ApplicationImpl
{
public:ApplicationImpl() {cout << "ApplicationImpl ..." << endl;}~ApplicationImpl() {cout << "~ApplicationImpl ..." << endl;}void Run(){cout << "Run ..." << endl;}
};typedef Singleton<ApplicationImpl> Application;int main() {Application::GetInstance().Run();Application::GetInstance().Run();return 0;
}