Objects and lazy iteration · Lesson 22 of 25

Inheritance and composition

Reuse behavior with an appropriate relationship.

8 minutes2 games

Inheritance models “is a”: class Student(Person). A subclass may add or override methods; super() follows the method resolution order. Composition stores another object as a field and often better represents “has a”.

Python

class Person:
    def __init__(self, name):
        self.name = name

    def greet(self):
        return f"Hi {self.name}"

class Student(Person):
    def __init__(self, name, level):
        super().__init__(name)
        self.level = level

student = Student("Mona", 2)
print(student.greet())
print(student.level)

Person
- Student
- Teacher

Quick question

A car has an engine. Which relationship is clearer?

Exercise

Make Dog inherit Animal and override sound to return woof. Print Dog().sound().

Expected output: woof

Python

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

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Python

Objects and lazy iteration · Lesson 22 of 25

Inheritance and composition

Reuse behavior with an appropriate relationship.

8 minutes2 games

Python

class Person:
    def __init__(self, name):
        self.name = name

    def greet(self):
        return f"Hi {self.name}"

class Student(Person):
    def __init__(self, name, level):
        super().__init__(name)
        self.level = level

student = Student("Mona", 2)
print(student.greet())
print(student.level)

Person
- Student
- Teacher

Quick question

A car has an engine. Which relationship is clearer?

Exercise

Make Dog inherit Animal and override sound to return woof. Print Dog().sound().

Expected output: woof

Python

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

Learn more from

Played 0 of 2 games