Skip to main content

Classes and Objects in Python

Object-Oriented Programming (OOP) in Python starts with the concepts of classes and objects.

What is a Class?​

A class is a blueprint or a template for creating objects. It defines a set of attributes that will characterize any object that is instantiated from this class.

What is an Object?​

An object is an instance of a class. It is a realized version of the class, containing actual data.

Instance vs. Class Variables​

  • Class Variables: Shared among all instances of a class. They are defined inside the class but outside any methods.
  • Instance Variables: Unique to each instance. They are defined inside methods, typically the __init__ method.

The __init__ Method​

The __init__ method is the constructor in Python. It is automatically called when a new instance of a class is created. It is used to initialize the object's state.

class Dog:
    # Class variable
    species = "Canis familiaris"

    def __init__(self, name, age):
        # Instance variables
        self.name = name
        self.age = age

    def description(self):
        return f"{self.name} is {self.age} years old."

# Creating objects
buddy = Dog("Buddy", 9)
miles = Dog("Miles", 4)

print(buddy.description())  # Output: Buddy is 9 years old.
print(miles.species)        # Output: Canis familiaris