Summary - Inheritance

Combine super and override to write a shape hierarchy.

Summary - Inheritance

In this group you learned inheritance, super(), overriding, multiple inheritance and isinstance/issubclass. A child class writes the parent in parentheses; super() calls parent methods.

With overriding the child redefines a parent method. Multiple inheritance uses comma-separated parents; MRO order decides. Now we will combine these pieces into one class.

Exercise Combine the Dog class

Define the Animal class; add def __init__(self, species): with self.species = species in the body and def speak(self): with print("Sound"). Then define class Dog(Animal):; add def __init__(self, name): with super().__init__("dog") and self.name = name; add def speak(self): with print("Woof"). Then call d = Dog("Rex"), print(d.name) and d.speak().

Show example solution

# Combine the Animal and Dog classes
class Animal:
    def __init__(self, species):
        self.species = species
    def speak(self):
        print("Sound")

class Dog(Animal):
    def __init__(self, name):
        super().__init__("dog")
        self.name = name
    def speak(self):
        print("Woof")

d = Dog("Rex")
print(d.name)
d.speak()

Test yourself

What is done inside child __init__?
- Parent __init__ is ignored
- Class name is changed
- Parent class is deleted
- super().__init__(...) is called
Show answer

super().__init__(...) is called — Inside child __init__, super().__init__(...) is called explicitly.
Match the concepts

class Dog(Animal)

Inheritance
super()

Parent call
def speak(self)

Override

Complete the child class definition

class Dog(____):
    pass

Show answer

class Dog(Animal):
    pass

Next lesson: Class design

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