Python self Parameter

The self Parameter

The self parameter is a reference to the current instance of the class.

It is used to access properties and methods that belong to the class.

Example

class Person:
  def __init__(self, name, age):
    self.name = name
    self.age = age

  def greet(self):
    print("Hello, my name is " + self.name)

p1 = Person("Emil", 25)
p1.greet()

Note: The self parameter must be the first parameter of any method in the class.

Why Use self?

Without self, Python would not know which object's properties you want to access:

Example

class Person:
  def __init__(self, name):
    self.name = name

  def printname(self):
    print(self.name)

p1 = Person("Tobias")
p2 = Person("Linus")

p1.printname()
p2.printname()

self Does Not Have to Be Named "self"

It does not have to be named self, you can call it whatever you like, but it has to be the first parameter of any method in the class:

Example

class Person:
  def __init__(myobject, name, age):
    myobject.name = name
    myobject.age = age

  def greet(abc):
    print("Hello, my name is " + abc.name)

p1 = Person("Emil", 36)
p1.greet()

Note: While you can use a different name, it is strongly recommended to use self as it is the convention in Python and makes your code more readable to others.

Accessing Properties with self

You can access any property of the class using self:

Example

class Car:
  def __init__(self, brand, model, year):
    self.brand = brand
    self.model = model
    self.year = year

  def display_info(self):
    print(f"{self.year} {self.brand} {self.model}")

car1 = Car("Toyota", "Corolla", 2020)
car1.display_info()

Calling Methods with self

You can also call other methods within the class using self:

Example

class Person:
  def __init__(self, name):
    self.name = name

  def greet(self):
    return "Hello, " + self.name

  def welcome(self):
    message = self.greet()
    print(message + "! Welcome to our website.")

p1 = Person("Tobias")
p1.welcome()