模板（四）

Singleton.h
#ifndef _SINGLETON_H_
#define _SINGLETON_H_

#include <cstdlib>
#include <iostream>
using namespace std;

template<typename T>
class Singleton {
public:
	static T& GetInstance() {
		//static T instance_; //局部静态对象
		//return instance_;
		Init();  //pthread_once();
		return *Singleton<T>::instance_;
	}
private:
	Singleton() {}
	~Singleton() {}
	Singleton(const Singleton& single) {}
	Singleton& operator=(const Singleton& single) {}
	static void Init() {
		if(NULL == Singleton<T>::instance_) {
			Singleton<T>::instance_ = new T;
			atexit(Destory);  //程序退出前调用，后面的会先调用
		}
	}
	static void Destory() {
		if(NULL != Singleton<T>::instance_) {
			delete Singleton<T>::instance_;
			Singleton<T>::instance_ = NULL;
		}
	}
	static T* instance_;
};


template<typename T>
T* Singleton<T>::instance_ = NULL;

#endif // _SINGLETON_H

main.cpp
#include <iostream>
#include "singleton.h"
using namespace std;

class ApplicationImpl {
public:
	ApplicationImpl() { cout <<"ApplicationImpl ..." << endl; }
	~ApplicationImpl() { cout <<"~ApplicationImpl ..." << endl; }
	void Run() {
		cout << "Run ..." << endl;
	}

};

typedef Singleton<ApplicationImpl> Application;

int main(void) {
	ApplicationImpl& app=Application::GetInstance();
	app.Run();
	Application::GetInstance().Run();
	Application::GetInstance().Run();
}

#!/bin/bash
g++ main.cpp -o test_main -std=c++11