#define NULLSUPPORT(x)\
	CLASSNAME(const Nuller&){ SetNull(); }\
	void SetNull(){ x=Null; }\
	bool IsNullInstance() const { return IsNull(x); }

class A{
public:
	typedef A CLASSNAME;

	NULLSUPPORT(a);

	int a;
	int b;

	A(){
		a=0;
		b=0;
	}
};