Kotlin Programming: The Big Nerd Ranch Guide, 2nd Edition

The Kotlin Type Hierarchy

If you do not specify a class to extend from, your class implicitly descends from a common superclass called Any. This means that every type in the language eventually extends from Any. In the case of your TownSquare class, the class hierarchy looks like Figure 15.2:

Figure 15.2  TownSquare type hierarchy

You can also use Any to define functions that accept any type of argument. Suppose that in NyetHack there are two things that can be a source of blessings: a blessed player or the room called The Fount of Blessings. A printIsSourceOfBlessings function, which checks and prints whether an object ...