Inheritance
Build new classes from existing ones — inherit all their attributes and methods, then add or customise what you need.
"Inheritance is reuse done right. Instead of copying code into a new class, you say 'this new class is a kind of that class' and get everything for free."
— ShurAIWhat is Inheritance?
Inheritance lets you create a new class that automatically gets all the attributes and methods of an existing class, plus its own additions. The existing class is the parent; the new class is the child:
Basic Inheritance
class Animal: # parent class
def __init__(self, name):
self.name = name
def breathe(self):
print(f"{self.name} breathes air.")
def sleep(self):
print(f"{self.name} is sleeping.")
class Dog(Animal): # Dog inherits from Animal
def bark(self): # Dog's own method
print(f"{self.name} says: Woof!")
d = Dog("Bruno")
d.breathe() # Bruno breathes air. — inherited from Animal
d.sleep() # Bruno is sleeping. — inherited from Animal
d.bark() # Bruno says: Woof! — Dog's own methodChild Class with Its Own __init__
The child can define its own __init__ and call the parent’s using super():
class Animal:
def __init__(self, name):
self.name = name
def describe(self):
print(f"Name: {self.name}")
class Dog(Animal):
def __init__(self, name, breed):
super().__init__(name) # call Animal's __init__ first
self.breed = breed # then add Dog's own data
def describe(self):
super().describe() # call parent's describe()
print(f"Breed: {self.breed}")
d = Dog("Bruno", "Labrador")
d.describe()
# Name: Bruno
# Breed: LabradorChecking Inheritance with isinstance()
d = Dog("Bruno", "Labrador")
print(isinstance(d, Dog)) # True — d is a Dog
print(isinstance(d, Animal)) # True — d is also an Animal
print(isinstance(d, Cat)) # False — d is not a CatReal Example — Employee Hierarchy
class Employee:
def __init__(self, name, salary):
self.name = name
self.salary = salary
def details(self):
print(f"{self.name} — ₹{self.salary}")
class Manager(Employee):
def __init__(self, name, salary, team_size):
super().__init__(name, salary)
self.team_size = team_size
def details(self):
super().details()
print(f" Manages a team of {self.team_size}")
e = Employee("Riya", 60000)
m = Manager("Arjun", 90000, 8)
e.details()
m.details()Riya — ₹60000
Arjun — ₹90000
Manages a team of 8"Use inheritance when there is a clear 'is a' relationship: a Dog IS an Animal. A Manager IS an Employee. If you can’t say 'is a', composition is probably better."
— ShurAI🧠 Quiz — Q1
What syntax creates a Dog class that inherits from Animal?
🧠 Quiz — Q2
If Dog inherits from Animal, which methods does a Dog object have?
🧠 Quiz — Q3
isinstance(d, Animal) returns True even though d is a Dog. Why?
🧠 Quiz — Q4
When a child class defines its own __init__, what must you do to set up the parent's attributes too?