Design Patterns Explained

Chapter 4 • A Standard Object-Oriented Solution 59
• visiot would be implemented by remembering the model it
belongs to and its ID in the V1 system when it is instantiated.
Then, whenever one of the visiot methods is called to get
information about it, the method would have to call a sequence
of subroutine calls in V1 to get that information.
• V2Slot would be implemented in a similar fashion, except
that, in this case, each V2Slot object would contain the slot
object corresponding to it in the V2 sys tem. Then, whenever
the object was asked for information, it would simply pass this
request on to the OOGSlot object and pass the response back to
the client object that originally requested it.
A more detailed diagram incorporating the V1 and V2 systems is
shown in Figure 4-3.
Figure 4-3 A first solution.