>It's not that Being is-a type of Inventory.
True. There are two schools of thought on this. First, is-a is a .......... to adhere to in the real world.Second, if is-a doesn't apply but you think inheritance could simplify your life, chances are good that your owning class' interface could be improved so that instead of just wrapping calls to the owned class' interface, you design an interface that still uses the owned class without duplicating its design. That usually results in more fluid interfaces across the board. It takes a great deal more effort though.
