oop07.py

import csv

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

    @classmethod # decorator to define a class method
    def instantiate_from_csv(cls):
        with open('oop07instances.csv', 'r') as f:
            reader = csv.DictReader(f)
            items = list(reader)

            for item in items:
                Item(
                    name = item.get('name'),
                    price = float(item.get('price')),
                    quantity = int(item.get('quantity')),
                )
        

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

# calling the class method to instantiate objects from CSV file
Item.instantiate_from_csv() 

# default all csv content is string
# so we need to convert them to appropriate data types
print(Item.all) # accessing all instances of Item class