class LazyProperty(object):

    def __init__(self, func):
        self.func = func

    def __get__(self, instance, owner):
        if instance is None:
            return self
        else:
            value = self.func(instance)
            # 这里直接覆盖了类的func.__name__值，所以再次调用时不是调用类的func函数
            setattr(instance, self.func.__name__, value)
            return value