I’m new to python programming, I’m trying to encapsulate all property checking of a size in the class object below but one of them is not working (checking to see if withdraw is bigger than amount of cookies inside the jar):
class Jar:
def __init__(self, capacity=12):
self.capacity = capacity
self._size = 0
def __str__(self):
return("🍪" * self.size)
def deposit(self, n):
self.size = n + self.size
def withdraw(self, n):
self.size = self.size - n
print(self.size)
@property
def capacity(self):
return self._capacity
@capacity.setter
def capacity(self, capacity):
if capacity < 0:
raise ValueError("None Positive Capacity")
self._capacity = capacity
@property
def size(self):
return self._size
@size.setter
def size(self, size):
print(self.size)
if self.size < 0:
raise ValueError("Insufficient Cookies")
if self.size > self.capacity:
raise ValueError("OverCapacity")
self._size = size
def main():
jar=Jar()
jar.deposit(12)
jar.withdraw(14)
print(jar)
if __name__ == "__main__":
main()
I expected that this would return a value error of insufficient cookies but it doesn’t. I’ve added print to the code to see the behavior. I’ve noticed that the withdraw method works but the resulting value isn’t checked by the size property setter.
>Solution :
You must use it like this, because the argument you give (size) is -14 and self.size is 0.
You should check size Instead self.size.
def size(self, size):
if size < 0:
raise ValueError("Insufficient Cookies")
if size > self.capacity:
raise ValueError("OverCapacity")
self._size = size
Do not forget to change the capacity value when increasing or decreasing the size.