class A {
BasePtr * ptr;
virtual BasePtr * getPtr() { return ptr; }
virtual void pure() = 0;
}

class B : public A {
B() : A() { ptr = new RoundPtr(); }
};

class C : public A {
C() : A() { ptr = new SquarePtr(); }
}

A * list[2];
list[0] = new B();
list[1] = new C();

list[i]->getPtr();