例如：
class Pizza:
def __init__(self, toppings):
self.toppings = toppings
self._pineapple_allowed = False
@property
def pineapple_allowed(self):
return self._pineapple_allowed
@pineapple_allowed.setter
def pineapple_allowed(self, value):
if value:
password = input("Enter the password: ")
if password == "Sw0rdf1sh!":
self._pineapple_allowed = value
else:
raise ValueError("Alert! Intruder!")
pizza = Pizza(["cheese", "tomato"])
print(pizza.pineapple_allowed)
pizza.pineapple_allowed = True
print(pizza.pineapple_allowed)
结果：
>>> False Enter the password: Sw0rdf1sh! True