9

OBJECT-ORIENTED PROGRAMMING

Many programmers believe that object-

oriented programming (OOP) makes for

clearer, more reusable code. Though very

different from the familiar OOP languages like

C++, Java, and Python, R is very much OOP in outlook.

The following themes are key to R:

• Everything you touch in R—ranging from numbers to character strings
  to matrices—is an object.


• R promotesencapsulation, which is packaging separate but related data
  items into one class instance. Encapsulation helps you keep track of
  related variables, enhancing clarity.


• R classes arepolymorphic, which means that the same function call leads
  to different operations for objects of different classes. For instance, a
  call toprint()on an object of a certain class triggers a call to a print
  function tailored to that class. Polymorphism promotes reusability.


• R allowsinheritance, which allows extending a given class to a more spe-
  cialized class.