from django.utils.functional import cached_property
import datetime

class User(object):
    birth_year = 1988

    @cached_property
    def age(self):
        return datetime.date.today().year - self.birth_year

if __name__ == '__main__':
    u = User()
    print(u.age)
    print(u.age)
　　
　　#结果
　　32
　　32