Python使用默认值用于回调协议参数
我正在尝试为特定的回调协议设置默认值（我希望callback类型的任何回调需要传递参数a，但可选地传递参数<代码> b ）。使用以下代码：
from typing import Protocol
from dataclasses import dataclass
class Callback(Protocol):
def __call__(self, a: str, b: str = "") -> None:
...
def foo(a: str, b: str) -> None:
print(a, b)
def bar(a: str, b: str = "") -> None:
print(a, b)
@dataclass(frozen=True)
class Foobar:
Foo: Callback
Bar: Callback
config = Foobar(Foo=foo, Bar=bar)
Mypy在抱怨：
(function) foo: (a: str, b: str) -> None
Argument of type "(a: str, b: str) -> None" cannot be assigned to parameter "Foo" of type "Callback" in function "__init__"
Type "(a: str, b: str) -> None" cannot be assigned to type "(a: str, b: str = "") -> None"
Parameter "b" is missing default argument PylancereportGeneralTypeIssues
Argument "Foo" to "Foobar" has incompatible type "Callable[[str, str], None]"; expected "Callback"mypy(error)
有没有办法使这项工作？搜索此特定错误，我什么都没有解决
I'm trying to set default values for a specific callback protocol (I'd like any callback of the Callback type to require passing in argument a but optionally pass in argument b). With the following code:
from typing import Protocol
from dataclasses import dataclass
class Callback(Protocol):
def __call__(self, a: str, b: str = "") -> None:
...
def foo(a: str, b: str) -> None:
print(a, b)
def bar(a: str, b: str = "") -> None:
print(a, b)
@dataclass(frozen=True)
class Foobar:
Foo: Callback
Bar: Callback
config = Foobar(Foo=foo, Bar=bar)
mypy is complaining with:
(function) foo: (a: str, b: str) -> None
Argument of type "(a: str, b: str) -> None" cannot be assigned to parameter "Foo" of type "Callback" in function "__init__"
Type "(a: str, b: str) -> None" cannot be assigned to type "(a: str, b: str = "") -> None"
Parameter "b" is missing default argument PylancereportGeneralTypeIssues
Argument "Foo" to "Foobar" has incompatible type "Callable[[str, str], None]"; expected "Callback"mypy(error)
Is there a way to make this work? Searching up this particular error gives me nothing to work off of
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如果我有一个
fb = foobar（...），我应该能够做fb.foo（“”），但是如果fb.foo是foo，因此类型错误if I have a
fb = Foobar(...), I should be able to dofb.Foo(""), but that wouldn't work iffb.Fooisfoo, hence the type error您在
__ Init __中定义了“ B”的类型，因此在下面重新定义它存在矛盾。根据您的含义，我认为您可以将“ B”作为可选参数。
You defined the type of "b" in
__init__, so there is a contradiction in redefining it below.According to your meaning, I think you could make "b" an optional parameter.