Inheritance & Method Overriding in Python0%

Inheritance & Method Overriding in Python

Intermediate8 min read•Updated: 2026-10-01

Inheritance & Method Overriding in Python

Inheritance is a cornerstone of Object-Oriented Programming that enables a child (derived) class to inherit attributes and methods from a parent (base) class. It facilitates clean code reuse, models hierarchical domain relationships ("is-a"), and allows subclasses to specialize or override behaviors.

1. Single Inheritance Basics

In Python, inheritance is declared by passing the parent class name inside parentheses after the child class definition:

1class Vehicle:
2    def __init__(self, brand: str, model: str):
3        self.brand = brand
4        self.model = model
5        self.speed = 0
6 
7    def accelerate(self, increment: int):
8        self.speed += increment
9        print(f"{self.brand} {self.model} accelerated to {self.speed} km/h.")
10 
11    def brake(self):
12        self.speed = 0
13        print(f"{self.brand} {self.model} brought to a stop.")
14 
15# Car inherits all attributes and methods from Vehicle
16class Car(Vehicle):
17    pass
18 
19my_car = Car("Tata", "Nexon")
20my_car.accelerate(50)  # Tata Nexon accelerated to 50 km/h.
21my_car.brake()         # Tata Nexon brought to a stop.

2. Extending Constructors with `super().init()`

When a child class needs its own unique attributes in addition to those of the parent, use the built-in super() function to invoke the parent class's constructor:

1class Vehicle:
2    def __init__(self, brand: str, model: str, year: int):
3        self.brand = brand
4        self.model = model
5        self.year = year
6 
7class ElectricCar(Vehicle):
8    def __init__(self, brand: str, model: str, year: int, battery_kwh: float):
9        # 1. Delegate core vehicle initialization to the parent class
10        super().__init__(brand, model, year)
11        
12        # 2. Initialize subclass-specific attribute
13        self.battery_kwh = battery_kwh
14        self.charge_percent = 100
15 
16    def charge(self):
17        self.charge_percent = 100
18        print(f"{self.brand} {self.model} battery charged to 100%.")
19 
20ev = ElectricCar("Tata", "Punch EV", 2024, 35.0)
21print(f"Vehicle: {ev.brand} {ev.model} ({ev.year}) | Battery: {ev.battery_kwh} kWh")
22ev.charge()

3. Method Overriding

Method Overriding occurs when a child class provides a custom implementation of a method that is already defined in its parent class.

Full Override vs. Cooperative Augmentation

1
Full Override: The child method completely replaces the parent method logic.
2
Augmentation: The child method runs custom logic before or after calling super().method_name().

1class Employee:
2    def __init__(self, name: str, base_salary: float):
3        self.name = name
4        self.base_salary = base_salary
5 
6    def calculate_annual_pay(self) -> float:
7        return self.base_salary * 12
8 
9    def display_role(self):
10        print(f"{self.name} is a standard corporate employee.")
11 
12 
13class Manager(Employee):
14    def __init__(self, name: str, base_salary: float, quarterly_bonus: float):
15        super().__init__(name, base_salary)
16        self.quarterly_bonus = quarterly_bonus
17 
18    # Method Overriding with Augmentation using super()
19    def calculate_annual_pay(self) -> float:
20        standard_pay = super().calculate_annual_pay()
21        total_bonuses = self.quarterly_bonus * 4
22        return standard_pay + total_bonuses
23 
24    # Complete Method Override
25    def display_role(self):
26        print(f"{self.name} is an Engineering Manager leading a team.")
27 
28emp = Employee("Ramesh", 50000)
29mgr = Manager("Sneha", 90000, 15000)
30 
31print(f"{emp.name} Annual Pay: ₹{emp.calculate_annual_pay():,.2f}")  # ₹600,000.00
32print(f"{mgr.name} Annual Pay: ₹{mgr.calculate_annual_pay():,.2f}")  # ₹1,140,000.00
33 
34emp.display_role()
35mgr.display_role()

4. Multiple Inheritance & Method Resolution Order (MRO)

Python supports multiple inheritance, where a class inherits from two or more parent classes. The order in which methods are resolved is dictated by the C3 Linearization algorithm, accessible via the mro() method or __mro__ attribute.

1class Device:
2    def ping(self):
3        print("Device responding.")
4 
5class WiFiEnabled(Device):
6    def ping(self):
7        print("WiFi Ping: Connected to router.")
8 
9class BluetoothEnabled(Device):
10    def ping(self):
11        print("Bluetooth Ping: Connected to paired unit.")
12 
13# Multiple inheritance order determines resolution
14class SmartSpeaker(WiFiEnabled, BluetoothEnabled):
15    pass
16 
17speaker = SmartSpeaker()
18speaker.ping()  # Output: WiFi Ping: Connected to router.
19 
20# Inspect the MRO path
21print([cls.__name__ for cls in SmartSpeaker.__mro__])
22# ['SmartSpeaker', 'WiFiEnabled', 'BluetoothEnabled', 'Device', 'object']

5. Type Introspection: `isinstance()` vs. `issubclass()`

Always use Python's built-in inspection functions rather than comparing raw type(obj) == Class:

1ev = ElectricCar("Tesla", "Model 3", 2023, 75.0)
2 
3# Check instance relationship
4print(isinstance(ev, ElectricCar))  # True
5print(isinstance(ev, Vehicle))      # True (inherited)
6print(isinstance(ev, object))       # True (root of all Python objects)
7 
8# Check class hierarchy relationship
9print(issubclass(ElectricCar, Vehicle))  # True
10print(issubclass(Vehicle, ElectricCar))  # False

⚠️ Common Intermediate Mistakes & Gotchas

1. Forgetting to Call `super().init()`

Failing to invoke super().__init__() leaves base class attributes uninitialized, resulting in unexpected AttributeErrors when derived methods execute.

2. Violating the Liskov Substitution Principle (LSP)

Overridden methods in child classes should accept the same parameters and return compatible data types as the parent method to prevent breaking caller expectations.

💻 Try It Yourself: Vehicle Hierarchy with Super()

Scenario

Define a base class Vehicle and a child class ElectricCar that extends __init__ with battery_capacity_kwh using super() and overrides drive() to display battery consumption.

Complete Solution

1class Vehicle:
2    def __init__(self, brand: str, model: str):
3        self.brand = brand
4        self.model = model
5 
6    def drive(self, distance_km: float):
7        print(f"Driving {self.brand} {self.model} for {distance_km} km.")
8 
9class ElectricCar(Vehicle):
10    def __init__(self, brand: str, model: str, battery_kwh: float):
11        super().__init__(brand, model)
12        self.battery_kwh = battery_kwh
13        self.charge_remaining = battery_kwh
14 
15    def drive(self, distance_km: float):
16        # Overridden method: consumes ~0.15 kWh per km
17        consumed = distance_km * 0.15
18        self.charge_remaining = max(0.0, self.charge_remaining - consumed)
19        print(f"⚡ Electric drive: {self.brand} {self.model} traveled {distance_km} km.")
20        print(f"Remaining Battery: {self.charge_remaining:.1f}/{self.battery_kwh} kWh")
21 
22ev = ElectricCar("Tata", "Nexon EV", 40.5)
23ev.drive(120)

Expected Output

1⚡ Electric drive: Tata Nexon EV traveled 120 km.
2Remaining Battery: 22.5/40.5 kWh

Interactive Quiz• Knowledge Check

Practice Quiz

Question 1

Which function is used in a child class constructor to call the parent class's __init__ method?

Question 2

What happens when a child class defines a method with the exact same name and signature as its parent class?

Question 3

What does MRO stand for in Python's object model?

Question 4

Which built-in function checks whether a specific class inherits from another class?

Question 5

If class Dog(Animal) does not define its own __init__ method, what constructor is executed when running Dog()?

🚀 What's Next?

In the next lesson, we will continue your intermediate Python journey with Polymorphism Basics (5: Object-Oriented Programming (Intermediate)).

👉 Continue to Next Lesson: Polymorphism Basics →

Next Lesson

Polymorphism Basics

Continue learning with hands-on practice, examples, and exercises in the upcoming topic.

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Previous Lesson	Next Lesson
Creating Classes & Objects (Review)	Polymorphism Basics

Practice Quiz

Test your understanding of this lesson with 5 questions. Each question has one correct answer.

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Polymorphism Basics

Inheritance & Method Overriding in Python

Intermediate8 min read•Updated: 2026-10-01

Study Materials Cheatsheet

Inheritance & Method Overriding in Python

1. Single Inheritance Basics

In Python, inheritance is declared by passing the parent class name inside parentheses after the child class definition:

1class Vehicle:
2    def __init__(self, brand: str, model: str):
3        self.brand = brand
4        self.model = model
5        self.speed = 0
6 
7    def accelerate(self, increment: int):
8        self.speed += increment
9        print(f"{self.brand} {self.model} accelerated to {self.speed} km/h.")
10 
11    def brake(self):
12        self.speed = 0
13        print(f"{self.brand} {self.model} brought to a stop.")
14 
15# Car inherits all attributes and methods from Vehicle
16class Car(Vehicle):
17    pass
18 
19my_car = Car("Tata", "Nexon")
20my_car.accelerate(50)  # Tata Nexon accelerated to 50 km/h.
21my_car.brake()         # Tata Nexon brought to a stop.

2. Extending Constructors with `super().init()`

When a child class needs its own unique attributes in addition to those of the parent, use the built-in super() function to invoke the parent class's constructor:

1class Vehicle:
2    def __init__(self, brand: str, model: str, year: int):
3        self.brand = brand
4        self.model = model
5        self.year = year
6 
7class ElectricCar(Vehicle):
8    def __init__(self, brand: str, model: str, year: int, battery_kwh: float):
9        # 1. Delegate core vehicle initialization to the parent class
10        super().__init__(brand, model, year)
11        
12        # 2. Initialize subclass-specific attribute
13        self.battery_kwh = battery_kwh
14        self.charge_percent = 100
15 
16    def charge(self):
17        self.charge_percent = 100
18        print(f"{self.brand} {self.model} battery charged to 100%.")
19 
20ev = ElectricCar("Tata", "Punch EV", 2024, 35.0)
21print(f"Vehicle: {ev.brand} {ev.model} ({ev.year}) | Battery: {ev.battery_kwh} kWh")
22ev.charge()

3. Method Overriding

Method Overriding occurs when a child class provides a custom implementation of a method that is already defined in its parent class.

Full Override vs. Cooperative Augmentation

1
Full Override: The child method completely replaces the parent method logic.
2
Augmentation: The child method runs custom logic before or after calling super().method_name().

1class Employee:
2    def __init__(self, name: str, base_salary: float):
3        self.name = name
4        self.base_salary = base_salary
5 
6    def calculate_annual_pay(self) -> float:
7        return self.base_salary * 12
8 
9    def display_role(self):
10        print(f"{self.name} is a standard corporate employee.")
11 
12 
13class Manager(Employee):
14    def __init__(self, name: str, base_salary: float, quarterly_bonus: float):
15        super().__init__(name, base_salary)
16        self.quarterly_bonus = quarterly_bonus
17 
18    # Method Overriding with Augmentation using super()
19    def calculate_annual_pay(self) -> float:
20        standard_pay = super().calculate_annual_pay()
21        total_bonuses = self.quarterly_bonus * 4
22        return standard_pay + total_bonuses
23 
24    # Complete Method Override
25    def display_role(self):
26        print(f"{self.name} is an Engineering Manager leading a team.")
27 
28emp = Employee("Ramesh", 50000)
29mgr = Manager("Sneha", 90000, 15000)
30 
31print(f"{emp.name} Annual Pay: ₹{emp.calculate_annual_pay():,.2f}")  # ₹600,000.00
32print(f"{mgr.name} Annual Pay: ₹{mgr.calculate_annual_pay():,.2f}")  # ₹1,140,000.00
33 
34emp.display_role()
35mgr.display_role()

4. Multiple Inheritance & Method Resolution Order (MRO)

1class Device:
2    def ping(self):
3        print("Device responding.")
4 
5class WiFiEnabled(Device):
6    def ping(self):
7        print("WiFi Ping: Connected to router.")
8 
9class BluetoothEnabled(Device):
10    def ping(self):
11        print("Bluetooth Ping: Connected to paired unit.")
12 
13# Multiple inheritance order determines resolution
14class SmartSpeaker(WiFiEnabled, BluetoothEnabled):
15    pass
16 
17speaker = SmartSpeaker()
18speaker.ping()  # Output: WiFi Ping: Connected to router.
19 
20# Inspect the MRO path
21print([cls.__name__ for cls in SmartSpeaker.__mro__])
22# ['SmartSpeaker', 'WiFiEnabled', 'BluetoothEnabled', 'Device', 'object']

5. Type Introspection: `isinstance()` vs. `issubclass()`

Always use Python's built-in inspection functions rather than comparing raw type(obj) == Class:

1ev = ElectricCar("Tesla", "Model 3", 2023, 75.0)
2 
3# Check instance relationship
4print(isinstance(ev, ElectricCar))  # True
5print(isinstance(ev, Vehicle))      # True (inherited)
6print(isinstance(ev, object))       # True (root of all Python objects)
7 
8# Check class hierarchy relationship
9print(issubclass(ElectricCar, Vehicle))  # True
10print(issubclass(Vehicle, ElectricCar))  # False

⚠️ Common Intermediate Mistakes & Gotchas

1. Forgetting to Call `super().init()`

Failing to invoke super().__init__() leaves base class attributes uninitialized, resulting in unexpected AttributeErrors when derived methods execute.

2. Violating the Liskov Substitution Principle (LSP)

Overridden methods in child classes should accept the same parameters and return compatible data types as the parent method to prevent breaking caller expectations.

💻 Try It Yourself: Vehicle Hierarchy with Super()

Scenario

Define a base class Vehicle and a child class ElectricCar that extends __init__ with battery_capacity_kwh using super() and overrides drive() to display battery consumption.

Complete Solution

1class Vehicle:
2    def __init__(self, brand: str, model: str):
3        self.brand = brand
4        self.model = model
5 
6    def drive(self, distance_km: float):
7        print(f"Driving {self.brand} {self.model} for {distance_km} km.")
8 
9class ElectricCar(Vehicle):
10    def __init__(self, brand: str, model: str, battery_kwh: float):
11        super().__init__(brand, model)
12        self.battery_kwh = battery_kwh
13        self.charge_remaining = battery_kwh
14 
15    def drive(self, distance_km: float):
16        # Overridden method: consumes ~0.15 kWh per km
17        consumed = distance_km * 0.15
18        self.charge_remaining = max(0.0, self.charge_remaining - consumed)
19        print(f"⚡ Electric drive: {self.brand} {self.model} traveled {distance_km} km.")
20        print(f"Remaining Battery: {self.charge_remaining:.1f}/{self.battery_kwh} kWh")
21 
22ev = ElectricCar("Tata", "Nexon EV", 40.5)
23ev.drive(120)

Expected Output

1⚡ Electric drive: Tata Nexon EV traveled 120 km.
2Remaining Battery: 22.5/40.5 kWh

Interactive Quiz• Knowledge Check

Practice Quiz

Question 1

Which function is used in a child class constructor to call the parent class's __init__ method?

Question 2

What happens when a child class defines a method with the exact same name and signature as its parent class?

Question 3

What does MRO stand for in Python's object model?

Question 4

Which built-in function checks whether a specific class inherits from another class?

Question 5

If class Dog(Animal) does not define its own __init__ method, what constructor is executed when running Dog()?

🚀 What's Next?

In the next lesson, we will continue your intermediate Python journey with Polymorphism Basics (5: Object-Oriented Programming (Intermediate)).

👉 Continue to Next Lesson: Polymorphism Basics →

Next Lesson

Polymorphism Basics

Continue learning with hands-on practice, examples, and exercises in the upcoming topic.

Related Lessons

Previous Lesson	Next Lesson
Creating Classes & Objects (Review)	Polymorphism Basics

Practice Quiz

Test your understanding of this lesson with 5 questions. Each question has one correct answer.

Previous Next

Inheritance & Method Overriding in Python

1. Single Inheritance Basics

2. Extending Constructors with super().__init__()

3. Method Overriding

Full Override vs. Cooperative Augmentation

4. Multiple Inheritance & Method Resolution Order (MRO)

5. Type Introspection: isinstance() vs. issubclass()

⚠️ Common Intermediate Mistakes & Gotchas

1. Forgetting to Call super().__init__()

2. Violating the Liskov Substitution Principle (LSP)

💻 Try It Yourself: Vehicle Hierarchy with Super()

Scenario

Complete Solution

Expected Output

Practice Quiz

🚀 What's Next?

Polymorphism Basics

Related Lessons

Practice Quiz

Loading Page Content...

Inheritance & Method Overriding in Python

1. Single Inheritance Basics

2. Extending Constructors with super().__init__()

3. Method Overriding

Full Override vs. Cooperative Augmentation

4. Multiple Inheritance & Method Resolution Order (MRO)

5. Type Introspection: isinstance() vs. issubclass()

⚠️ Common Intermediate Mistakes & Gotchas

1. Forgetting to Call super().__init__()

2. Violating the Liskov Substitution Principle (LSP)

💻 Try It Yourself: Vehicle Hierarchy with Super()

Scenario

Complete Solution

Expected Output

Practice Quiz

🚀 What's Next?

Polymorphism Basics

Related Lessons

Practice Quiz

2. Extending Constructors with `super().init()`

5. Type Introspection: `isinstance()` vs. `issubclass()`

1. Forgetting to Call `super().init()`

2. Extending Constructors with `super().init()`

5. Type Introspection: `isinstance()` vs. `issubclass()`

1. Forgetting to Call `super().init()`