Day 11 of 30: 🏷️ Object-Oriented Programming Basics

Learn how to model real-world things in code using classes and objects

May 11, 2025

🔄 Quick Recap (Day 10)

You mastered dictionaries for key:value storage.
You created, accessed, modified, and removed dictionary entries.

🎯 What You’ll Learn Today

What classes and objects are in Python.
How to define a simple class with attributes.
How to create instances (objects) of your class.
How to add methods (functions) to classes.

📖 Overview: Classes and Objects

Think of a class as a blueprint (like a recipe) and an object as the baked dish (the result). Classes define attributes (data) and methods (actions) that their objects will have.

class Dog:
    def __init__(self, name, age):
        self.name = name      # attribute
        self.age = age        # attribute

    def bark(self):
        print(f"{self.name} says woof!")  # method

class Dog: starts the class definition.
__init__ is a special method called when creating an object.
self refers to the specific object instance.

📖 Creating Objects and Using Methods

Instantiation

Create an object by calling the class:

my_dog = Dog("Buddy", 3)

Accessing Attributes and Calling Methods

print(my_dog.name)  # Buddy
print(my_dog.age)   # 3
my_dog.bark()       # Buddy says woof!

🧙‍♂️ Take the Wand and Try Yourself

Create a file named animal.py.
Define a class Animal with:
- An __init__ method accepting species and sound.
- A method make_sound() that prints: "A [species] goes [sound]!".
Instantiate two different animals (e.g., cat, dog) and call make_sound() on each.

Solution Example (animal.py):

# animal.py
class Animal:
    def __init__(self, species, sound):
        self.species = species
        self.sound = sound

    def make_sound(self):
        print(f"A {self.species} goes {self.sound}!")

# Create instances
cat = Animal("cat", "meow")
dog = Animal("dog", "woof")

# Use methods
cat.make_sound()  # A cat goes meow!
dog.make_sound()  # A dog goes woof!

Expected output:

A cat goes meow!
A dog goes woof!

Run:

python animal.py

Once your script prints the correct sounds, you’ve mastered basic classes and objects!

Ready for Day 12: Inheritance & Polymorphism? See you there!

Day 11 of 30: 🏷️ Object-Oriented Programming Basics

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