Chapter 3. Creational Patterns

In the last chapter we took a long look at how to fashion a class. In this chapter we'll look at how to create instances of classes. On the surface it seems like a simple concern but how we create instances of a class can be of great importance.

We take great pains in creating our code so that it be as decoupled as possible. Ensuring that classes have minimal dependence on other classes is the key to building a system that can change fluently with the changing needs of those using the software. Allowing classes to be too closely related means that changes ripple through them like, well, ripples.

One ripple isn't a huge problem but, as you throw more and more changes into the mix, the ripples add up and create interference patterns. Soon the once placid surface is an unrecognizable mess of additive and destructive nodes. This same problem occurs in our applications: the changes magnify and interact in unexpected ways. One place where we tend...