python - 如何将一个类中所有对象共享的变量增加 1？

Question

我如何编写一个名为 nextyear() 的函数，使所有动物的年龄增加 1？

class Animal:
  def __init__(self, age):
    self.age=age
animal1 = Animal (5)
animal2 = Animal (7)
animal3 = Animal (3)

Answer 1

你可以使用一个类变量和一个属性:

class Animal:
    year = 0

    def __init__(self, age):
        self._age = age - self.__class__.year

    @property
    def age(self):
        return self._age + self.__class__.year

    @classmethod
    def next_year(cls):
        cls.year += 1


animal1, animal2, animal3 = Animal(5), Animal(7), Animal(3)

for animal in (animal1, animal2, animal3):
    print(animal.age)

print("Next year:")
Animal.next_year()
for animal in (animal1, animal2, animal3):
    print(animal.age)