public static void VirtualFunc(out int r1, out int r2)
{
BaseClass o1 = new BaseClass();
BaseClass o2 = new DrivenClass();
r1 = o1.Foo();
r2 = o2.Foo();
}
public static int ItfWithRefParam(ref int a, out int b)
{
ItfWithRefParam o = new DrivenClass();
return(o.WithRefParam(ref a, out b));
}