Hello everyone, I’m Leo.
This is the final episode of the Python Beginner Series — thank you for joining the journey!
We’ve covered everything from basic syntax to modules. Now we bring it all together.
In episode 6, we built a simple inventory manager using functions and dictionaries.
Today, we refactor it using Object-Oriented Programming to see how classes make the code cleaner, more organized, and ready for growth.
This is the moment everything clicks — I hope you feel the same satisfaction I did when I first refactored a project with OOP.
Quick Answer: What is Refactoring?
Refactoring means improving existing code without changing what it does — making it cleaner, more readable, and easier to extend.
Why Refactor with OOP?
OOP refactoring gives you:
- Clear separation of data and behavior
- Easier maintenance and extension
- Natural modeling of real-world entities
- Code that scales gracefully
Beginner-Friendly Explanation
Before OOP, our inventory was just loose dictionaries and functions — like running a restaurant with notes scattered on the counter.
With OOP, we create an Inventory class — a proper system that keeps everything organized in one place, just like a professional restaurant management dashboard.
Complete Code: OOP Refactored Inventory Manager
Save as inventory_oop.py:
class RestaurantInventory:
def __init__(self, name):
self.name = name
self.stock = {
"Beef": 50,
"Noodles": 100,
"Vegetables": 30,
"Chili": 20,
"Eggs": 60
}
self.alert_level = 25
def show_low_stock(self):
print(f"=== {self.name} Low Stock Alert ===")
low_items = []
for item, quantity in self.stock.items():
if quantity < self.alert_level:
low_items.append(f"{item}: only {quantity} left")
if low_items:
for warning in low_items:
print(warning)
else:
print("All ingredients well stocked — ready to serve!")
def check_item(self, item_name):
if item_name in self.stock:
status = "LOW!" if self.stock[item_name] < self.alert_level else "sufficient"
print(f"{item_name}: {self.stock[item_name]} portions → {status}")
else:
print(f"{item_name} not in inventory")
def update_stock(self, item_name, change):
if item_name in self.stock:
self.stock[item_name] += change
action = "added" if change > 0 else "used"
print(f"{item_name}: {abs(change)} portions {action} → now {self.stock[item_name]}")
else:
print(f"{item_name} not found")
# Create inventory object
my_restaurant = RestaurantInventory("Leo's Beef Noodles")
# Daily operations
print("Morning report:")
my_restaurant.show_low_stock()
print("")
my_restaurant.check_item("Vegetables")
my_restaurant.update_stock("Vegetables", -10) # Used in cooking
my_restaurant.update_stock("Beef", 30) # New delivery
print("\nEnd-of-day report:")
my_restaurant.show_low_stock()
Before vs After OOP Refactor
| Aspect | Before (Functions) | After (OOP) | Restaurant Analogy |
|---|---|---|---|
| Data & Behavior | Separate | Bundled together | Scattered notes vs organized dashboard |
| Multiple Restaurants | Hard | Easy (multiple objects) | Single stall vs chain franchise |
| Code Organization | Flat | Structured | Loose papers vs filing system |
| Future Extensions | Messy | Clean | Hard to expand vs ready to grow |
Learning Steps Summary
- Step 1: Move data into __init__
- Step 2: Turn functions into methods (add self)
- Step 3: Create object to use the class
- Step 4: Call methods on the object
- Step 5: Enjoy cleaner, more professional code
Common Questions About OOP Refactoring (FAQ)
Q: Does OOP make code slower?
A: No — the performance difference is negligible for most applications.
Q: Should every project use OOP?
A: Not always — small scripts can stay simple. Use OOP when modeling real things or building larger systems.
Q: What’s next after this series?
A: Backend development with Flask — turning your projects into web applications!
Congratulations — you’ve completed the Python Beginner Series!
From your first print statement to refactoring with OOP, you’ve built real skills and a practical project.
You’re no longer a beginner — you’re ready to create useful programs and explore backend development.
Thank you for learning with me. Keep coding, keep building, and never stop being curious!
Leo January 3, 2026