Key characteristics of inheritance:
Let’s look at an example to illustrate inheritance:
class Animal:
def __init__(self, name):
self.name = name
def speak(self):
pass
class Dog(Animal):
def speak(self):
return f"{self.name} says Woof!"
class Cat(Animal):
def speak(self):
return f"{self.name} says Meow!"
# Creating instances
dog = Dog("Buddy")
cat = Cat("Whiskers")
print(dog.speak()) # Output: Buddy says Woof!
print(cat.speak()) # Output: Whiskers says Meow!
# Demonstrating polymorphism
def animal_sound(animal):
print(animal.speak())
animal_sound(dog) # Output: Buddy says Woof!
animal_sound(cat) # Output: Whiskers says Meow!
In this example, we have a base class Animal and two derived classes Dog and Cat. Both Dog and Cat inherit from Animal and override the speak method.
Here’s a UML diagram representing this inheritance relationship:
classDiagram
class Animal {
+name: string
+speak()
}
class Dog {
+speak()
}
class Cat {
+speak()
}
Animal <|-- Dog
Animal <|-- Cat
end
In this diagram, the arrows pointing from Dog and Cat to Animal indicate inheritance. This shows that Dog and Cat are subclasses of Animal.
Inheritance is a powerful feature of OOP, but it should be used judiciously. Overuse of inheritance can lead to complex class hierarchies that are difficult to understand and maintain. The principle of “composition over inheritance” suggests that it’s often better to use composition (has-a relationship) rather than inheritance (is-a relationship) when designing class relationships.
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