SingletonOnce

SingletonOnce.hpp

/*
 * SingletonOnce.hpp
 *
 *  Created on: Jan 9, 2015
 *      Author: wencan
 */

#ifndef SINGLETONCALLONCE_HPP_
#define SINGLETONONCE_HPP_

#include <memory>
#include <mutex>

/**
 * 单例模板
 * 使用C++ 11的call_once保证多线程环境下之后构建对象一次
 * 使用共享指针，确保单例对象最后被析构
 *
 * wencan
 * 2015-01-09
 */
template<typename T>
class SingletonOnce
{
//protected:
//	SingletonOnce() {};
//public:
//	virtual ~SingletonOnce() {};
//private:
//	SingletonOnce<T> (const SingletonOnce<T> &){}
//	SingletonOnce<T> & operator = (const SingletonOnce<T> &){}
public:
	static std::shared_ptr<T> Instance()
	{
		std::call_once(m_once_flag, [](){SingletonOnce<T>::m_instance.reset(new T());});
		return m_instance;
	}
private:
	static std::shared_ptr<T> m_instance;
	static std::once_flag m_once_flag;
};

template<typename T>
std::shared_ptr<T> SingletonOnce<T>::m_instance;

template<typename T>
std::once_flag SingletonOnce<T>::m_once_flag;

#endif /* SINGLETONONCE_HPP_ */