Flake8给出F832未定义名称，尽管使用";从__future_导入注释"

Question

我有这个pyi文件。

from __future__ import annotations
import datetime

class Payment:
amount: float = ...
date: datetime.date = ...
def set_amount(self: Payment, amount: float = Amounts.Null):
...
def get_amount(self: Payment) -> float:
...
def get_date(self: Payment) -> datetime.date:
...

class Amounts:
Null: float = ...

使用from __future__ import annotations有助于删除self参数的F821 undefined name 'Payment'警告。

然而，flake8仍然显示F821 undefined name 'Amounts'。可以以某种方式修复此警告吗(不完全禁用F821(？或者这可能是一个bug？

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注意，我在Python 3.10.0上使用flake8 4.0.1 (mccabe: 0.6.1, pycodestyle: 2.8.0, pyflakes: 2.4.0)。

Answer 1

错误没有错：

$ python3 t.pyi
Traceback (most recent call last):
File "t.pyi", line 5, in <module>
class Payment:
File "t.pyi", line 9, in Payment
def set_amount(self: Payment, amount: float = Amounts.Null):
NameError: name 'Amounts' is not defined

__future__annotations推迟注释，但您稍后在文件中有一个引用类的默认值(它不是注释！(

一种选择是简单的重新排序：

from __future__ import annotations
import datetime

class Amounts:
Null: float = ...

class Payment:
amount: float = ...
date: datetime.date = ...
def set_amount(self: Payment, amount: float = Amounts.Null):
...
# ...

更好的是完全省略默认值，因为它在pyi(或存根函数(中什么都不做：

from __future__ import annotations
import datetime

class Payment:
amount: float = ...
date: datetime.date = ...
def set_amount(self: Payment, amount: float = ...):
# ...

还要注意，您的函数有点不正确——现在类型检查器会将set_amount解释为-> Any，因为您省略了返回值，正确的做法是-> None

您可以采取的另一种方法是通过# noqa、per-file-ignores或其他方式忽略错误——尽管这可能不是您想要做的，因为代码已损坏

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