饿汉模式单例模板

#ifndef SINGLETON_H
#define SINGLETON_H
#include <memory>
#include <mutex>

//单例模板

template <typename T>
class Singleton {
public:
    static T& GetInstance();

private:
    static std::unique_ptr<T> instance;
};

template <typename T>
std::unique_ptr<T> Singleton<T>::instance;

template <typename T>
T& Singleton<T>::GetInstance()
{
    std::once_flag sflag;
    std::call_once(sflag, [&](){
        instance.reset(new T());
    });
    return *instance;
}



#define SINGLETON(Class)                           public:                                                ~Class() = default;                            private:                                               Class() = default;                                 Class(const Class &other) = delete;                Class& operator=(const Class &other) = delete;     friend class Singleton<Class>;                 
#endif // SINGLETON_H