oop06.py

# creating a class

class Item:
    pay_rate = 0.8 # The pay rate after 20% discount
    all = [] # list to store all instances of Item class
    # constructor
    def __init__(self, name: str, price: float, quantity=0):
        # Run validation to the received arguments
        assert price >= 0, f"Price {price} is not greater than or equal to zero!"
        assert quantity >=0, f"Quantity {quantity} is not greater than or equal to zero!"

        # assigning to self object
        self.name = name            # instance attributes
        self.price = price          # instance attributes
        self.quantity = quantity    # instance attributes

        # append the instance to the all list
        Item.all.append(self)

    def calculate_total_price(self):
        return self.price * self.quantity
    
    def apply_discount(self):
        # self.price = self.price * Item.pay_rate # accessing class attribute via class
        self.price = self.price * self.pay_rate # accessing class attribute via insta nce

    # __repr__ method to return a string representation of the object
    def __repr__(self):
        return f"Item('{self.name}', {self.price}, {self.quantity})"

item1 = Item("phone", 100, 5) 
item2 = Item("Laptop", 1000, 6)
item3 = Item("Tablet", 500, 3)
item4 = Item("Monitor", 300, 4)
item5 = Item("Keyboard", 50, 10)

print(Item.all) # accessing all instances of Item class

for instance in Item.all:
    print(instance.name)