DECLARE
v_parent parent_type := parent_type ('PARENT 1');
v_child child_type := child_type ('CHILD 1', 10);
BEGIN
v_parent.eat; -- works OK, parent procedure is executed
v_child.eat; -- works OK, child procedure is executed

v_parent := v_child; -- polymorphic assignment
v_parent.eat; -- works OK, child procedure is executed
END;

/

Parent procedure: PARENT 1 eats
Child procedure: CHILD 1 eats
Child procedure: CHILD 1 eats