Inheritance is one of the core concepts of Object-Oriented Programming (OOP) in Python. It allows you to define a new class that inherits properties and methods from an existing class. This promotes code reuse, modularity, and hierarchy in your program.
What is Inheritance?
Inheritance allows one class (called the child class or subclass) to inherit the attributes and methods of another class (called the parent class or base class).
Why Use Inheritance?
-
Reuse existing code
-
Add or override features in the child class
-
Build hierarchies of classes
-
Promote cleaner and DRY (Don't Repeat Yourself) code
Syntax of Inheritance
class Parent:
# parent class code
class Child(Parent):
# child class code
✅ Basic Example
class Animal:
def speak(self):
print("I am an animal")
class Dog(Animal):
def bark(self):
print("Woof!")
d = Dog()
d.speak() # Inherited from Animal
d.bark() # Defined in Dog
Overriding Methods
A child class can override methods of the parent class.
class Animal:
def speak(self):
print("Generic animal sound")
class Cat(Animal):
def speak(self):
print("Meow!")
c = Cat()
c.speak() # Meow!
Using super() to Call Parent Methods
The super() function is used to call a method from the parent class.
class Animal:
def __init__(self, name):
self.name = name
def speak(self):
print("Animal sound")
class Dog(Animal):
def __init__(self, name, breed):
super().__init__(name) # Call parent constructor
self.breed = breed
def speak(self):
super().speak() # Call parent method
print("Woof!")
d = Dog("Buddy", "Labrador")
d.speak()
Output:
Animal sound
Woof!
Types of Inheritance in Python
| Type | Description | Example |
|---|---|---|
| Single Inheritance | Child inherits from one parent | class B(A) |
| Multiple Inheritance | Child inherits from more than one parent | class C(A, B) |
| Multilevel Inheritance | Inheritance chain: A → B → C | class C(B) where B(A) |
| Hierarchical Inheritance | Multiple children from a single parent | class B(A), class C(A) |
Multiple Inheritance Example
class Father:
def skills(self):
print("Gardening, Driving")
class Mother:
def skills(self):
print("Cooking, Teaching")
class Child(Father, Mother):
def skills(self):
super().skills() # Uses first parent in MRO
print("Python Programming")
c = Child()
c.skills()
Output:
Gardening, Driving
Python Programming
Note: Python uses Method Resolution Order (MRO) to decide the order in which base classes are searched.
Multilevel Inheritance Example
class Grandparent:
def house(self):
print("Big house")
class Parent(Grandparent):
def car(self):
print("BMW")
class Child(Parent):
def bike(self):
print("Yamaha")
c = Child()
c.house() # Inherited from Grandparent
c.car() # Inherited from Parent
c.bike() # Defined in Child
Practical Example: Employee Management System
class Employee:
def __init__(self, name, salary):
self.name = name
self.salary = salary
def show(self):
print(f"Name: {self.name}, Salary: {self.salary}")
class Manager(Employee):
def __init__(self, name, salary, department):
super().__init__(name, salary)
self.department = department
def show(self):
super().show()
print(f"Department: {self.department}")
m = Manager("Alice", 90000, "IT")
m.show()
Output:
Name: Alice, Salary: 90000
Department: IT
⚠️ Common Pitfalls
| Pitfall | Description | Fix |
|---|---|---|
Forgetting super() in subclass |
Parent attributes not initialized | Always call super().__init__() |
| Name collision | Child method overrides parent unintentionally | Be careful when naming methods |
| Multiple inheritance confusion | Method Resolution Order can be complex | Use mro() to inspect class hierarchy |
print(Child.mro())
Tips and Best Practices
-
✅ Use inheritance only when there’s a clear “is-a” relationship
-
✅ Prefer composition over inheritance when possible
-
✅ Keep class hierarchies simple and intuitive
-
✅ Use
super()to enhance base methods, not replace them blindly -
✅ Document overridden methods clearly
Summary Table
| Term | Description |
|---|---|
class Child(Parent) |
Creates a subclass |
super() |
Calls method from parent class |
__init__() |
Constructor, used to initialize attributes |
mro() |
Method Resolution Order of classes |
Final Challenge: Build Your Own System
Try building a class hierarchy like this:
Vehicle (base)
├── Car
│ └── ElectricCar
└── Bike
Add features like speed, fuel_type, and override methods such as start() and stop() in child classes.
Tips and Tricks
What is pass in Python?
Python | Pass Statement
The pass statement is used as a placeholder for future code. It represents a null operation in Python. It is generally used for the purpose of filling up empty blocks of code which may execute during runtime but has yet to be written.
def myfunction():
pass
How can you generate random numbers?
Python | Generate random numbers
Python provides a module called random using which we can generate random numbers. e.g: print(random.random())
We have to import a random module and call the random() method as shown below:
import random
print(random.random())
The random() method generates float values lying between 0 and 1 randomly.
To generate customized random numbers between specified ranges, we can use the randrange() method
Syntax: randrange(beginning, end, step)
import random
print(random.randrange(5,100,2))
What is lambda in Python?
Python | Lambda function
A lambda function is a small anonymous function. This function can have any number of parameters but, can have just one statement.
Syntex:
lambda arguments : expression
a = lambda x,y : x+y
print(a(5, 6))
It also provides a nice way to write closures. With that power, you can do things like this.
def adder(x):
return lambda y: x + y
add5 = adder(5)
add5(1) #6
As you can see from the snippet of Python, the function adder takes in an argument x and returns an anonymous function, or lambda, that takes another argument y. That anonymous function allows you to create functions from functions. This is a simple example, but it should convey the power lambdas and closures have.
What is swapcase() function in the Python?
Python | swapcase() Function
It is a string's function that converts all uppercase characters into lowercase and vice versa. It automatically ignores all the non-alphabetic characters.
string = "IT IS IN LOWERCASE."
print(string.swapcase())
How to remove whitespaces from a string in Python?
Python | strip() Function | Remove whitespaces from a string
To remove the whitespaces and trailing spaces from the string, Python provides a strip([str]) built-in function. This function returns a copy of the string after removing whitespaces if present. Otherwise returns the original string.
string = " Python "
print(string.strip())
What is the usage of enumerate() function in Python?
Python | enumerate() Function
The enumerate() function is used to iterate through the sequence and retrieve the index position and its corresponding value at the same time.
lst = ["A","B","C"]
print (list(enumerate(lst)))
#[(0, 'A'), (1, 'B'), (2, 'C')]
Can you explain the filter(), map(), and reduce() functions?
Python | filter(), map(), and reduce() Functions
- filter() function accepts two arguments, a function and an iterable, where each element of the iterable is filtered through the function to test if the item is accepted or not.
>>> set(filter(lambda x:x>4, range(7))) # {5, 6}
-
map() function calls the specified function for each item of an iterable and returns a list of result
>>> set(map(lambda x:x**3, range(7))) # {0, 1, 64, 8, 216, 27, 125}
-
reduce() function reduces a sequence pair-wise, repeatedly until we arrive at a single value..
>>> reduce(lambda x,y:y-x, [1,2,3,4,5]) # 3Let’s understand this:
2-1=1
3-1=2
4-2=2
5-2=3Hence, 3.
What is a namedtuple?
Python | namedtuple
A namedtuple will let us access a tuple’s elements using a name/label. We use the function namedtuple() for this, and import it from collections.
>>> from collections import namedtuple
#format
>>> result=namedtuple('result','Physics Chemistry Maths')
#declaring the tuple
>>> Chris=result(Physics=86,Chemistry=92,Maths=80)
>>> Chris.Chemistry
# 92
Write a code to add the values of same keys in two different dictionaries and return a new dictionary.
We can use the Counter method from the collections module
from collections import Counter
dict1 = {'a': 5, 'b': 3, 'c': 2}
dict2 = {'a': 2, 'b': 4, 'c': 3}
new_dict = Counter(dict1) + Counter(dict2)
print(new_dict)
# Print: Counter({'a': 7, 'b': 7, 'c': 5})
Python In-place swapping of two numbers
Python | In-place swapping of two numbers
>>> a, b = 10, 20
>>> print(a, b)
10 20
>>> a, b = b, a
>>> print(a, b)
20 10
Reversing a String in Python
Python | Reversing a String
>>> x = 'PythonWorld'
>>> print(x[: : -1])
dlroWnohtyP
Python join all items of a list to convert into a single string
Python | Join all items of a list to convert into a single string
>>> x = ["Python", "Online", "Training"]
>>> print(" ".join(x))
Python Online Training
python return multiple values from functions
Python | Return multiple values from functions
>>> def A():
return 2, 3, 4
>>> a, b, c = A()
>>> print(a, b, c)
2 3 4
Python Print String N times
Python | Print String N times
>>> s = 'Python'
>>> n = 5
>>> print(s * n)
PythonPythonPythonPythonPython
Python check the memory usage of an object
Python | Check the memory usage of an object
>>> import sys
>>> x = 100
>>> print(sys.getsizeof(x))
28
