Recall

Often, we'll spot really good ideas that are repeated; the repetition can form a recognizable pattern. Exploiting a pattern-based approach to software design can save the developer from wasting time trying to reinvent something already well understood. In this chapter, we looked at a few more advanced design patterns:

• An Adapter class is a way to insert an intermediary so a client can make use of an existing class even when the class is not a perfect match. The software adapter parallels the idea of USB hardware adapters between various kinds of devices with various USB interface connectors.
• The Façade pattern is a way to create a unified interface over a number of objects. The idea parallels the façade of a building that unifies separate floors, rooms, and halls into a single space.
• We can leverage the Flyweight pattern to implement a kind of lazy initialization. Instead of copying objects, we can design Flyweight classes that share a...