Manager objects
We've been focused on objects and their attributes and methods. Now, we'll take a look at designing higher-level objects; the kind of objects that manage other objects – the objects that tie everything together. These are sometimes called Façade objects because they present a pleasant, easy-to-use façade over some underlying complexity. See Chapter 12, Advanced Design Patterns, for an additional look at the Façade design pattern.
Most of the previous examples tend to model concrete ideas. Management objects are more like office managers; they don't do the actual visible work out on the floor, but without them, there would be no communication between departments, and nobody would know what they are supposed to do (although, this can be true anyway if the organization is badly managed!). Analogously, the attributes on a management class tend to refer to other objects that do the visible work; the behaviors...