Python · Quick Reference

Lesson 12 — Inheritance & Polymorphism Cheat Sheet

Python

In one line: Inheritance lets a child class automatically get all the attributes and methods of a parent class. The child can then add new methods or override existing ones. This is the "is-...

Key Ideas

1Basic Inheritance. Inheritance lets a child class automatically get all the attributes and methods of a parent class. The child can then add new methods or override existing ones. This i...

2Polymorphism in Action. Polymorphism means "many forms." In Python, it means you can write a function that accepts any object and calls a method on it — and each object responds in its own wa...

3Abstract Base Classes. Sometimes you want to create a parent class that cannot be instantiated directly and forces every subclass to implement certain methods. Python's ABC (Abstract Base Cl...

4Multiple Inheritance & MRO. Python allows a class to inherit from multiple parents. When the same method exists in multiple parents, Python uses the Method Resolution Order (MRO) — determined by ...

Code Examples

# Parent class (base class)
class Animal:
    def __init__(self, name, species):
        self.name    = name
        self.species = species
        self.energy  = 100

    def eat(self, food):
        self.energy += 10
        return f"{self.name} eats {foo...

# Polymorphism — one function, many types
def animal_concert(animals):
    """Make every animal speak — works for any Animal subclass."""
    for animal in animals:
        print(animal.speak())   # each responds differently

class Bird(Animal):
    def __i...

from abc import ABC, abstractmethod

class Shape(ABC):
    """Abstract base — every shape MUST implement area and perimeter."""

    @abstractmethod
    def area(self):
        pass

    @abstractmethod
    def perimeter(self):
        pass

    # Non-abstr...