Inherited methods which return a base class instance

[smani]

Hi,

consider this inheritance of MyVector from MyPoint:

class MyPoint {
/* ... */
    public MyPoint add(MyPoint other){ ... }
}

class MyVector extends MyPoint {
/* ... */
}

/* somewhere in the code */
MyVector v1 = new MyVector(...);
MyVector v2 = new MyVector(...);

MyVector v3 = v1.add(v2); // Error, cannot cast from MyPoint to MyVector

I wonder whether I really must override all base class member functions just to change the return type, or is there a more elegant way to solve this problem?

Thanks!