Python, adding a "cashback" for every third iteration-CodePudding

Our professor gave us a problem of adding a "cashback" mechanism for an online store setting. We are tasked to use a parent class and a child class to use inheritance.

Goal: to add 50 after every third purchase

What I have so far:

Parent:

class Shop:

    def __init__(self):
        self.__balance = 0

    def getBalance(self):
        return self.__balance

    def loadWallet(self, amount):
        self.__balance  = amount

    def purchase(self, amount_val):
        if amount_val <= self.__balance:
            self.__balance -= amount_val

        else:
            print("Insufficient Funds")

Child:

class ShopCashBack(Shop):

    def __init__(self, base_val=0):
        self.__numpurchase = base_val
        Shop.__init__(self)

    def getPurch(self):
        return self.__numpurchase

    def purchase(self, amount_val):
        self.__numpurchase  = 1

        Shop.purchase(self, amount_val)

        if self.__numpurchase % 3 == 0:
            result = self.getBalance()   50
            print(result)

Input:

user = ShopCashBack()

user.loadWallet(5000)
user.purchase(299)
print(user.getBalance())

user.loadWallet(3000)
print(user.getBalance())
user.purchase(4990)
print(user.getBalance())

user.purchase(1607)
print(user.getBalance())

Result:

Desired Result: where 1154 is 1104 50 (the balance after the third purchase)

CodePudding user response：

you need to change child perchase method

from this:

if self.__numpurchase % 3 == 0:
    result = self.getBalance()   50
    print(result)

to this:

if self.__numpurchase % 3 == 0:
    self.loadWallet(50)

because you don't do anything to balance with result = self.getBalance() 50 balance stays the same after this line