如何输入提示动态创建的数据类

Question

我讨厌写两次东西，所以我想出了一个不错的方法来不必写两次东西。然而，这似乎打破了我的类型提示：

from enum import Enum
from dataclasses import make_dataclass, field, dataclass

class DatasetNames(Enum):
    test1 = "test1_string"
    test2 = "test2_string"
    test3 = "test3_string"

def get_path(s: str) -> str:
    return s + "_path"

# the normal way to do this, but I have to type every new dataset name twice
# and there's a lot of duplicate code
@dataclass(frozen=True)
class StaticDatasetPaths:
    test1 = get_path("test1_string")
    test2 = get_path("test2_string")
    test3 = get_path("test3_string")

# mypy recognizes that `StaticDatasetPaths` is a class
# mypy recognizes that `StaticDatasetPaths.test2` is a string
print(StaticDatasetPaths.test2) # 'test2_string_path'

# this is my way of doing it, without having to type every new dataset name twice and no duplicate code
DynamicDatasetPaths = make_dataclass(
    'DynamicDatasetPaths', 
    [
        (
            name.name,
            str,
            field(default=get_path(name.value))
        )
        for name in DatasetNames
    ],
    frozen=True
)

# mypy thinks `DynamicDatasetPaths` is a `variable` of type `type`
# mypy thinks that `DynamicDatasetPaths.test2` is an `function` of type `Unknown`
print(DynamicDatasetPaths.test2) # 'test2_string_path'

如何让mypy知道DynamicDatasetPaths是一个属性为字符串的冻结数据类？

通常，当我遇到这样的情况时，我可以只使用

cast

并告诉 mypy 正确的类型是什么，但我不知道“属性为字符串的冻结数据类”的正确类型。

（另外，如果有更好的方法来避免重复的代码，我也很高兴听到这一点。）

Answer 1

数据类旨在创建实例。由于您不是实例化数据类，而是访问

test1

、

test2

等作为类属性，因此您可以简单地将

get_path

设为

Enum

类的方法：

from enum import Enum

class DatasetNames(Enum):
    test1 = "test1_string"
    test2 = "test2_string"
    test3 = "test3_string"

    def get_path(self) -> str:
        return self.value + '_path'

print(DatasetNames.test2.get_path()) # outputs test2_string_path