Summary

In this chapter, you've learned when it is a good idea to create a custom class. You've learned about the five principles of SOLID design, and the trade-offs involved in applying them to Ruby classes. You've learned about the important trade-off when deciding how many classes should make up your application. You've also learned when it is appropriate to use custom data structures instead of the core data structures. Now you have a better understanding of the principles of a Ruby class design and the trade-offs between different design approaches.

In the next chapter, you'll learn all about Ruby's different types of variables, and how best to use each of them.