Decorator
In the previous chapter, we discussed the Prototype design pattern, which allowed for creating instances of classes with slightly (or not so slightly) different data.
What if we would like to create a set of classes with slightly different behavior though? Well, since functions in Kotlin are first-class citizens (more on that in a bit), you could use the Prototype design pattern to achieve that. After all, that's what JavaScript does successfully. But the goal of this chapter is to discuss another approach to the same problem. After all, design patterns are all about approaches.
By implementing this design pattern, we allow the user of our code to specify which abilities he or she wants to add.
Enhancing a class
Your boss—sorry, scrum master—came to you yesterday with an urgent requirement. From now on, all map data structures in your system are to become HappyMaps.
What, you don't know what HappyMaps are? They are the hottest stuff going around right now. They are just like the regular...
