Accessing items within a class in Python? - python-3.x

Question

I am very new to Object oriented programming and I am having trouble accessing items in my class when I run my main method. My program is trying to allow a user to add item prices to a cart until they are finished and prints the number of items and total.
class CashRegister:
print("Welcome to shopping world!")
def __init__(self, price):
self.price = price
def addItem(self, price):
CashRegister.totalPrice = CashRegister.totalPrice + price
CashRegister.itemCount = CashRegister.itemCount + 1
#property
def getTotal(self):
return totalPrice
#property
def getCount(self):
return itemCount
def main():
selection = "Y"
while selection != "N":
selection = input("Would you like to add another item to the
cart Y or N")
selection = selection.upper()
if selection == "Y":
price = input("What is the price of the item?")
CashRegister.addItem(price)
else:
print(CashRegister.getCount)
print(CashRegister.getTotal)
print(selection)
main()
Here is the error I am getting when I select yes:
TypeError: addItem() missing 1 required positional argument: 'price'
Here is the output I am getting when I select no:
Welcome to shopping world!
Would you like to add another item to the cart Y or Nn
<property object at 0x0000022CFFCA2598>
<property object at 0x0000022CFFCA2548>
N

Answer 1

first, you don't use the class name for declaring variables in its methods: you have self for that (which you can rename to whatever you like, but 'self' is convention)
second, you have to initialize your class object in the main function, otherwise Python won't know what to do with the methods you call (when you define a method in a class, the first argument self stands for the class object, so each time you initialize an object and then call a method on that, the argument you pass inside the brackets is actually the second argument, first one being the object itself)
third: this is more of a style thing, but you don't really use CamelCase in python except for names of classes, all the rest is in snake_case
fourth: += is more readable and faster than example = example + 1
class CashRegister(object) :
def __init__(self) :
self.total_price = 0
self.item_count = 0
def add_item(self, price) :
self.total_price += int(price)
self.item_count += 1
def get_total(self) :
return self.total_price
def get_count(self) :
return self.item_count
def main() :
register = CashRegister()
selection = True
while selection :
selection = input("Would you like to add another item to the cart Y or N\n\t").upper()
if selection == "Y" :
price = input("What is the price of the item?\n\t")
register.add_item(price)
else :
print(register.get_total())
print(register.get_count())
print(selection)
selection = False
main()
this is how I would probably do it, I've taken out the #property decorators because I don't know if you really have a need for them there, you can just call the methods with brackets () at the end to get what you want
Then, there's a bunch more stuff you should do if you really want to to use this, and that would be exception catching, determine how the cash register behaves if a negative value is passed as price, and so on... good luck and enjoy Python

Answer 2

you have many mistakes you need the determine totalprice and itemcount in self, you need to determine a variable with cashregister class
class CashRegister:
print("Welcome to shopping world!")
def __init__(self):
self.totalPrice=0
self.itemCount=0
def addItem(self, price):
self.totalPrice = self.totalPrice + price
self.itemCount = self.itemCount + 1
#property
def getTotal(self):
return self.totalPrice
#property
def getCount(self):
return self.itemCount
def main():
selection = "Y"
box=CashRegister()
while selection != "N":
selection = input("Would you like to add another item to thecart Y or N\n\t:")
selection = selection.upper()
if selection == "Y":
price = input("What is the price of the item?\n\t:")
box.addItem(int(price))
else:
print(box.getCount)
print(box.getTotal)
print(selection)
main()