Chapter 8. S3 Classes

This is the second chapter in our introduction to programming. In the preceding chapter, we explored the basic control structures that help us to define the code that is executed, and we had our first taste of objects. We will now build on the idea of object-oriented programming, concentrating on S3 classes. There are two approaches, S3 and S4 classes. It is common for some people to use only one exclusively.

This chapter is divided into three parts:

• Defining classes and methods: This section will give a general idea of how methods are defined whose function depends on the class name of the primary argument
• Objects and inheritance: In this section, we will discuss the way in which objects of a given class can be defined; we will also introduce the idea of inheritance in the context of S3 classes
• Encapsulation: In this section, we will discuss the importance of encapsulation with respect to a class and how it is handled within the context of an R class

At first...