#include<boost/noncopyable.hpp>

//#include "../sort.h"

//#include "getLeastNumber.h"

#include<set>

using namespace std;

template<typename T>

class Singleton:boost::noncopyable{

public:

    static T& instance(){

        pthread_once(&ponce_,&Singleton::init);

        return *value_;

    }

private:

    Singleton();

    ~Singleton();

    static void init(){

        value_ = new T();

    }

private:

    static pthread_once_t ponce_;

    static T* value_;

};

template<typename T>

pthread_once_t Singleton<T>::ponce_ = PTHREAD_ONCE_INIT;

template<typename T>

T* Singleton<T>::value_ = nullptr;

class Foo{

public:

    Foo(){};

    ~Foo(){};

    void show(){std::cout<<"begin"<<"\nend"<<std::endl;}

};

int main() {

    //A bfs;

    //bfs.test();

    Foo& foo = Singleton<Foo>::instance();

    foo.show();

    return ;

}