In this chapter, we learned about structural design patterns including Composite, Decorator, Adapter, Bridge, Façade, Flyweight, and Proxy. Again we found some of these patterns are highly inter related and even similar to each other to some degree.

For example, we mixed Composite Pattern with Decorator Pattern, Adapter Pattern with Proxy Pattern, compared Adapter Pattern and Bridge Pattern. During the journey of exploring, we sometimes found it was just a natural result to have our code end in a pattern that's similar to what we've listed if we took writing better code into consideration.

Taking Adapter Pattern and Bridge Pattern as an example, when we are trying to make two classes cooperate, it comes out with Adapter Pattern and when we are planning on connecting with different classes in advance, it goes with Bridge Pattern. There are no actual lines between each pattern and the applications of those patterns, though the techniques behind patterns could usually be useful.

In the next chapter, we are going to talk about behavioral patterns that help to form algorithms and assign the responsibilities.