这种叫什么手法

class CallbackA {
 public:
	virtual void funcA() = 0;
	virtual void funcB() = 0;
};

class Base : public CallbackA {
 public:
	void func()
	{
		std::cout << "func" << std::endl;
	}
	virtual void funcA()
	{
		std::cout << "funcA" << std::endl;
	}
	virtual void funcB()
	{
		std::cout << "funcB" << std::endl;
	}
};

class ClassA {
 public:
	ClassA() : cbA(nullptr) {}

	void testA()
	{
		std::cout << "ClassA TestA\t";
		cbA->funcA();
	}
	void testB()
	{
		std::cout << "ClassA TestB\t";
		cbA->funcB();
	}
	void setCallBack(CallbackA* cb) {cbA = cb;}

 private:
	CallbackA* cbA;
};

int main()
{
	Base *b = new Base();
	b->func();
	b->funcA();
	ClassA *d = new ClassA();
	d->setCallBack(b);
	
	d->testA();
	d->testB();

	return 0;
}