singleton.h

#define SINGLETON(klass) \
private:\
	static inline klass * mpInstance = nullptr;\
public:\
	template <class... Args>\
	static void createInstance(Args... args) noexcept\
	{\
		if(mpInstance == nullptr)\
		{\
			mpInstance = new klass(args...);\
		}\
	}\
	static void destroyInstance() noexcept\
	{\
		delete mpInstance;\
		mpInstance = nullptr;\
	}\
	static klass & instance() { return *mpInstance; }