OOP with Python

demo_oop.py

class BankAccount():
    def __init__(self, first_name, last_name, balance=0):
        self.__first_name = first_name
        self.__last_name = last_name
        self.__balance = balance

    def withdraw(self, amount):
        if(self.balance < amount):
            return False

        self.__balance -= amount
        return True

    def credit(self, amount):
        if(amount < 0):
            return False

        self.__balance += amount
        return True

    @property
    def first_name(self):
        return self.__first_name

    @property
    def last_name(self):
        return self.__last_name

    @property
    def balance(self):
        return self.__balance

    def __str__(self):
        return "{} {}".format(self.first_name, self.last_name)

class Person():
    def __init__(self, first_name, last_name):
        self.__first_name = first_name
        self.__last_name = last_name
        self.__bank_account = None

    def create_bank_account(self, initial_amount=0):
        self.__bank_account = BankAccount(self.first_name, self.last_name, initial_amount)

    def has_bank_account(self):
        return self.bank_account is not None

    @property
    def first_name(self):
        return self.__first_name

    @property
    def bank_account(self):
        return self.__bank_account

    @property
    def last_name(self):
        return self.__last_name

    @property
    def balance(self):
        if(self.has_bank_account()):
            return self.bank_account.balance
        raise NotImplementedError

    def purchase(self, cart):
        if(self.has_bank_account()):
            return self.bank_account.withdraw(cart.total_price())
        raise NotImplementedError

    def __str__(self):
        return "{} ({})".format(self.first_name, self.last_name)


class Item():
    def __init__(self, name, price, quantity):
        self.__name = name
        self.__price = price
        self.__quantity = quantity

    @property
    def quantity(self):
        return self.__quantity

    def total_price(self):
        return self.__price * self.__quantity

    def __str__(self):
        return "{} x{} = {}".format(
            self.__name,
            self.__quantity,
            self.total_price()
        )

class Cart():
    def __init__(self, items=[]):
        self.__items = items

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

    def add_items(self, items):
        self.__items.extend(items)

    @property
    def items(self):
        return self.__items

    def total_quantity(self):
        total_quantity = 0

        for item in self.items:
            total_quantity += item.quantity

        return total_quantity

    def total_price(self):
        total_price = 0

        for item in self.items:
            total_price += item.total_price()

        return total_price

    def __str__(self):
        return str([str(item) for item in self.items])

################################
honore = Person('Honore', 'Hounwanou')
# honore.create_bank_account(10000)

item1 = Item('Mac Book Pro', 3500, 1)
item2 = Item('Keyboard', 50, 1)

cart = Cart([item1, item2])

cart.add_item(Item('Microphone', 250, 1))

item4 = Item('USB Key', 30, 3)
item5 = Item('MacBook Pro', 3900,1)

cart.add_items([item4, item5])

print(cart)
print(honore.balance)
print(cart.total_price())
print(honore.purchase(cart))
print(honore.balance)