๐ Lesson 3: Inheritance
1. What is inheritance?
In short โ Inheritance is an OOP concept where a parent class (base class)'s code can be reused in a child class (derived class).
In detail โ Inheritance allows a child class to reuse and extend the functionality of a parent class.
2. Why Inheritance?
- Reuse existing code
- Avoid duplication
- Extend functionality easily
- Model real-world hierarchies (e.g., Animal โ Dog, Cat)
3. Summary
โ Inheritance = reuse + extend parent class
โ
super() โ call parent methods
โ Supports single, multiple, multilevel, hierarchical inheritance
โ Helps model real-world hierarchies
python
# ===== 1. Parent class =====
class Animal:
def __init__(self, name):
self.name = name
def speak(self):
return f"{self.name} makes a sound."
# ===== 2. Child class =====
class Dog(Animal):
def speak(self):
return f"{self.name} says Woof!"
class Cat(Animal):
def speak(self):
return f"{self.name} says Meow!"
# ===== 3. Create objects =====
dog = Dog("Bobby")
cat = Cat("Kitty")
print(dog.speak()) # Bobby says Woof!
print(cat.speak()) # Kitty says Meow!
# ===== 4. super() Keyword =====
class Bird(Animal):
def __init__(self, name, can_fly=True):
super().__init__(name) # call parent constructor
self.can_fly = can_fly
bird = Bird("Eagle")
print(f"\n{bird.speak()}") # Eagle makes a sound.
# ===== 5. Multiple Inheritance =====
class Flyer:
def fly(self):
return "I can fly!"
class Swimmer:
def swim(self):
return "I can swim!"
class Duck(Flyer, Swimmer):
pass
d = Duck()
print(f"\n{d.fly()}") # I can fly!
print(d.swim()) # I can swim!You should see
Bobby says Woof! Kitty says Meow! Eagle makes a sound. I can fly! I can swim!