Methods

Learn methods and self inside a class.

Defining methods

A method is a function defined inside a class. A method starts with def; its first parameter is always self.

Example: class Book:\n def describe(self):\n print("Book"). Here describe is the method name; self points to the instance. Defining a method does not run it; it waits to be called: b.describe().

The self parameter

self points to the instance that calls the method. Inside a method you access instance data with self.attribute. The call does not pass self explicitly; Python sends it automatically.

Example: b = Book(); b.describe(). Here describe(self) is called with self being the instance b. This way the method uses the right instance's data. Another name could replace self, but self is the convention.

Exercise Add a method to the Book class

Define a class named Book. Add a method def describe(self): whose body is print("Book"). After the class, create an instance with b = Book() and call b.describe().

Show example solution

# Define the Book class and the describe method
class Book:
    def describe(self):
        print("Book")

b = Book()
b.describe()

Test yourself

Match the parts of a method

def

Keyword
describe

Method name
self

Instance reference
What is the first parameter of a method?
- cls
- this
- self
- instance
Show answer

self — An instance method's first parameter is self; the instance is passed automatically.

Complete the method signature

class Book:
    def describe(____):
        print("Book")

Show answer

class Book:
    def describe(self):
        print("Book")

Next lesson: __init__

We Are Enhancing Your Experience

Cookie Preferences

Strictly Necessary Cookies

Analytical Cookies