Why Restaurant, Menu, Order classes in LLD? - Purpose & Use Cases

The Big Idea

What if a simple class design could save your restaurant from chaos and mistakes?

The Scenario

Imagine running a busy restaurant where you write down every menu item, customer order, and bill by hand on paper.

When a customer orders, you scramble to find the right dish details and calculate the total manually.

The Problem

This manual method is slow and confusing.

Orders get mixed up, menu changes are hard to track, and mistakes in bills happen often.

It's stressful and wastes time, especially when many customers come at once.

The Solution

Using Restaurant, Menu, and Order classes organizes everything clearly.

The Menu class holds all dishes, the Order class tracks what customers want, and the Restaurant class manages it all.

This setup makes adding, updating, and processing orders fast and error-free.

Before vs After

✗ Before

menu = ['Pizza', 'Burger']
order = ['Pizza']
total = 0
if 'Pizza' in order:
    total += 10

✓ After

class Menu:
    def __init__(self):
        self.items = {'Pizza': 10, 'Burger': 8}

class Order:
    def __init__(self):
        self.items = []

    def add_item(self, item):
        self.items.append(item)

menu = Menu()
order = Order()
order.add_item('Pizza')
total = sum(menu.items[item] for item in order.items)

What It Enables

This design lets restaurants handle many orders smoothly and update menus instantly without confusion.

Real Life Example

Think of a popular pizza place where customers order different toppings and sizes.

Classes help the staff quickly see what each customer wants and prepare the right pizza without mistakes.

Key Takeaways

Manual tracking is slow and error-prone.

Classes organize menu and orders clearly.

Design improves speed and accuracy in restaurants.