Python Guide | Quantum Repository

Python Fundamentals: Classes

In Python, a class is a blueprint for creating objects. Classes encapsulate data and functions as methods.

a. Defining and creating an object of a class: Define a class using the 'class' keyword and then create its objects.

Code

class Dog:
    def bark(self):
        return "Woof!"

dog = Dog()
print(dog.bark())

Output

Woof!

b. Initialisation with '__init__': The '__init__' method is a special method that is run when an object is instantiated.

Code

class Cat:
    def __init__(self, name):
        self.name = name
    def meow(self):
        return f"{self.name} says Meow!"

cat = Cat("Whiskers")
print(cat.meow())

Output

Whiskers says Meow!

c. Inheritance: Python classes can inherit properties and methods from other classes.

Code

class Animal:
    def speak(self):
        return "Some sound"

class Cow(Animal):
    def speak(self):
        return "Moo"

cow = Cow()
print(cow.speak())

Output

Moo

d. In the above example the Cow class is overriding the speak method of the Animal class. If you want to also include the sound of the parent Animal class when the Cow speaks, you can call the parent method inside the speak method of the Cow class using the super() function.

Code

class Animal:
    def speak(self):
        return "Some sound"

class Cow(Animal):
    def speak(self):
        return super().speak() + " and Moo"

cow = Cow()
print(cow.speak())

Output

Some sound and Moo