design pattern singleton

멀티스레드 개발에서 일관성을 보장해주는 방식

• 생성자 막기
• 소멸자 막기
• getter
• multithread

// C++
Foo* Foo::Instance() {
  if(pinstance == nullptr) {
    lock_guard<mutex> lock(m_);
    if(pinstance == nullptr) {
        pinstance = new Foo();
    }
  }
  return pinstance;
}

// JAVA
public static synchronized singleton getInstance () {
    if (instance == null)
        instance = new ThreadSafeInitalization();
    return instance;
}

접기 1. 주소 값을 이용한 방식

 
class yh_singleton
{
public:
	static yh_singleton& getInstanse(){
		static yh_singleton instance;
		return instance;
	};
	int num;
private:
	yh_singleton(){};
	yh_singleton(const yh_singleton& other);
	yh_singleton& operator=(yh_singleton& cls);
	~yh_singleton(){};
};

yh_singleton& yh= yh_singleton::getInstanse();
yh.num= 4;

2. 포인터를 이용한 방식

 
class yh_singleton
{
public:
	static yh_singleton* getInstanse(){
		static yh_singleton instance;
		return &instance;
	};
	int num;
private:
	yh_singleton(){};
	yh_singleton(const yh_singleton& other);
	yh_singleton& operator=(yh_singleton& cls);
	~yh_singleton(){};
};

yh_singleton* yh= yh_singleton::getInstanse();
yh->;num= 4;

3. 템플릿 싱글톤

 
template <typename T>
class yh_singleton
{
public:
	static T* getInstance()
	{
		if (instance == NULL)
			instance = new T;
		return instance;
	};

	static void destroyInstance()
	{
		if (instance)
		{
			delete instance;
			instance = NULL;
		}
	};
private:
	static T* instance;
protected:
	yh_singleton(const yh_singleton& other);
	yh_singleton& operator=(yh_singleton& cls);
	yh_singleton();
	virtual ~yh_singleton(){};
};
template <typename T>T * yh_singleton<T>::instance = NULL;

class ojectA : public yh_singleton<ojectA>
{
public:
	ojectA();
	~ojectA();

	int a;
};