12.3 OOP: Properties

12.3.1 Objects have class

• Class defines:
  • Method (i.e., what can be done with object)
  • Fields (i.e., data that defines an instance of the class)
• Objects are an instance of a class

12.3.2 Class is inherited

• Class is defined:
  • By an object’s class (e.g., ordered factor)
  • By the parent of the object’s class (e.g., factor)
• Inheritance matters for method dispatch
  • If a method is defined for an object’s class, use that method
  • If an object doesn’t have a method, use the method of the parent class
  • The process of finding a method, is called dispatch