Python 数据类 AttributeError

Question

我有一个这样设置的数据类：

from dataclasses import dataclass, field
from typing import List

@dataclass
class stats:
    target_list: List[None] = field(default_factory=list)

当我尝试像这样比较列表的内容时：

if stats.target_list == None:
    pass

我得到 AttributeError: type object 'stats' has no attribute 'target_list'

我该如何解决这个问题？谢谢

Answer 1

target_list您正在尝试查找以类本身命名的属性。您想要测试该类的对象。例如：

from dataclasses import dataclass, field
from typing import List

@dataclass
class stats:
    target_list: List[None] = field(default_factory=list)


def check_target(s):
    if s.target_list is None:
        print('No target list!')
    else:
        print(f'{len(s.target_list)} targets')


StatsObject1 = stats()
StatsObject2 = stats(target_list=['a', 'b', 'c'])

check_target(StatsObject1)
check_target(StatsObject2)