Instantiating script class from method of another class?

Hi, This might be a silly newbie question, but how can I in script instatiate a class by calling a method from another class? Say in script I'd like to do something like this:

Foo a;
Bar b = a.getNewBar(); 

In C++, I'd have something like this:

class Bar {
	Bar();
	void Addref();
	void ReleaseRef();
};

class Foo {
	Foo();
	void Addref();
	void ReleaseRef();
	Bar* getNewBar() {return new Bar();}
};

I've tried to find a suitable function registration to do that, but I'm not getting anything working.  I'm assuming that class Bar should be without factory, is that correct …