🧬 Python Inheritance – Reuse and Extend Class Functionality

🧲 Introduction – Why Use Inheritance in Python?

In object-oriented programming, inheritance allows one class to reuse attributes and methods of another. It improves code reusability, encourages DRY (Don’t Repeat Yourself) principles, and allows for logical class hierarchy design.

Python supports multiple types of inheritance, including single, multiple, multilevel, and hierarchical.

🎯 In this guide, you’ll learn:

• What inheritance is and why it matters
• The different types of inheritance in Python
• How to use super() to access parent methods
• Real-world examples
• Best practices and common mistakes

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✅ What Is Inheritance?

Inheritance is a mechanism where a new class (child or subclass) inherits properties and behaviors from an existing class (parent or base class).

class Parent:
    def speak(self):
        print("Speaking from Parent")

class Child(Parent):
    pass

c = Child()
c.speak()  # Inherits speak() from Parent

✅ Output:

Speaking from Parent

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🔁 Types of Inheritance in Python

Type	Description
Single	One child class inherits from one parent class
Multiple	One child class inherits from multiple parents
Multilevel	Class inherits from a class that is also a child
Hierarchical	Multiple children inherit from one parent

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🔹 1. Single Inheritance

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

class Dog(Animal):
    def breed(self):
        return "Labrador"

d = Dog()
print(d.sound())  # Inherited
print(d.breed())  # Own method

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🔹 2. Multiple Inheritance

class Father:
    def skills(self):
        return ["Gardening", "Carpentry"]

class Mother:
    def skills(self):
        return ["Cooking", "Art"]

class Child(Father, Mother):
    def skills(self):
        return super().skills() + ["Python"]

c = Child()
print(c.skills())  # Output depends on MRO (Method Resolution Order)

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🔹 3. Multilevel Inheritance

class Grandparent:
    def speak(self):
        print("Hello from grandparent")

class Parent(Grandparent):
    def listen(self):
        print("Listening in parent")

class Child(Parent):
    def play(self):
        print("Playing in child")

c = Child()
c.speak()
c.listen()
c.play()

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🔹 4. Hierarchical Inheritance

class Vehicle:
    def start(self):
        print("Engine started")

class Bike(Vehicle):
    pass

class Car(Vehicle):
    pass

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🔧 Using super() Function

Use super() to call methods of the parent class:

class Person:
    def greet(self):
        print("Hello!")

class Student(Person):
    def greet(self):
        super().greet()
        print("Hi, I’m a student.")

✅ Output:

Hello!
Hi, I’m a student.

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⚠️ Common Mistakes in Inheritance

❌ Mistake	✅ Fix
Overriding without super()	Always use super() to extend parent functionality
Ignoring MRO in multiple inheritance	Use consistent method resolution order
Mixing unrelated classes in hierarchy	Use composition instead of inheritance when needed

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📘 Best Practices for Python Inheritance

✅ Do This	❌ Avoid This
Use inheritance to express “is-a” relationships	Forcing unrelated classes into inheritance
Favor composition over multiple inheritance	Deep, confusing inheritance chains
Use super() for clean extensibility	Duplicating code from the parent class
Keep your base class focused and reusable	Making the base class too general or large

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📌 Summary – Recap & Next Steps

Inheritance in Python allows developers to reuse and extend class behavior, enabling code reuse and logical class structure.

🔍 Key Takeaways:

• ✅ Inheritance enables a child class to reuse parent attributes/methods
• ✅ Use super() to call parent class methods inside overrides
• ✅ Types: Single, Multiple, Multilevel, Hierarchical
• ✅ Avoid deep inheritance chains and misuse of super()

⚙️ Real-World Relevance:
Used in frameworks (like Django models), custom libraries, and domain modeling for building scalable software.

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❓ FAQ – Python Inheritance

❓ What is inheritance in Python?

✅ Inheritance is a mechanism where a new class derives behavior and properties from an existing class.

❓ Can a class inherit from multiple classes?

✅ Yes. Python supports multiple inheritance using comma-separated base classes.

class C(A, B): ...

❓ What does super() do?

✅ super() allows you to call methods of a parent class inside a child class, commonly used when overriding methods.

❓ How do I know the method resolution order (MRO)?

✅ Use:

print(ClassName.__mro__)

Or:

help(ClassName)

❓ Is inheritance better than composition?

⚠️ Use inheritance for “is-a” relationships, and composition for “has-a” relationships. Composition is often more flexible.

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