Inheritance

Class inheritance allows attributes and methods to be passed from one class to another. For example, suppose there is already a class available in a Python package that does almost everything you want. However, you just wish it had one extra method or attribute that would make it right for your purpose. Instead of rewriting the entire class, you could inherit the class and add additional properties, or change existing properties.

The DRY Principle Revisited

Recall the DRY principle: "Every piece of knowledge or logic must have a single, unambiguous representation within a system." So far in this chapter, we have seen how classes allow us to more elegantly encapsulate logic about what objects represent. This has already moved us further along the path to writing clean, modularized code. Inheritance is the next step in this journey. Suppose we wanted to create two classes, one representing cats and the other, dogs.

Our Cat class may look like this:

class...