装饰器注释

Question

我正在努力注释装饰器函数。
执行 mypy --strict . mypy 时抱怨：test.py:25: error: Untyped decorator makes function "func1" untyped.
据我所知，我的装饰器不是无类型的...
我可以更改的是装饰器的注释，我不能更改对象生成方式（类生成器和测试）或参数传递方式（实例化）背后的概念).

from typing import Dict, Any, List
import functools


def has_params(params: Dict[str, Any]) -> Any:
    def param_decorator(func: Any) -> Any:
        @functools.wraps(func)
        def func_decorator(*args: Any) -> Any:
            class_obj = args[0]
            for param in params:
                if (param not in class_obj.params.keys()):
                    raise Exception(f'Parameter {param} not passed to object, but required by function {class_obj.name}.{func.__name__}')
                if (not isinstance(class_obj.params[param], params[param])):
                    raise Exception(f'Parameter {param} for object {class_obj.name} has the wrong type, expected {params[param]}, got {type(class_obj.params[param])}')
            return func(*args)
        return func_decorator
    return param_decorator


class Test():
    def __init__(self) -> None:
        self.__params: Dict[str, Any] = dict()
        self.__name = "Test"

    @has_params(params={'param1': bool})
    def func1(self) -> None:
        # self.params['param1'] can be safely accessed here because it is type checked by @has_params
        print(f'Got param1: {self.params["param1"]}')

    @property
    def params(self) -> Dict[str, Any]:
        return self.__params
    @params.setter
    def params(self, value: Dict[str, Any]) -> None:
        self.__params = value
    @property
    def name(self) -> str:
        return self.__name


class Generator():
    def __init__(self) -> None:
        self.__obj_list: List[Test] = list()

    def add_elem(self, name: str, params: Dict[str, Any] = {}) -> None:
        obj = self._create_object_by_name(name)
        obj.params = params
        self.__obj_list.append(obj)

    def execute(self) -> None:
        for obj in self.__obj_list:
            obj.func1()

    def _create_object_by_name(self, class_name: str) -> Any:
        if class_name in globals():
            return globals()[class_name]()
        else:
            raise Exception(f'Class "{class_name}" is not defined')


gen = Generator()
gen.add_elem('Test', params={'param1': 7.5})
gen.execute()

Answer 1

我认为问题在于装饰器上的注释 return Any，而实际上它应该 return 一个 Callable。如果您将 has_params 尤其是 param_decorator 的 return 类型更改为 Callable[..., Any]，它会起作用。

或者更好的是，声明一个具有任意可调用对象上限的类型变量：

F = TypeVar('F', bound=Callable[..., Any])

并注释

def param_decorator(func: F) -> F: ...

更新： 自己测试时，我还必须添加：

    return cast(F, func_decorator)

在 param_decorator 的末尾，否则 mypy 抱怨

Incompatible return value type (got "Callable[[VarArg(Any)], Any]", expected "F")

我不确定是否有更好的方法来处理通用函数包装，尽管这似乎与 mypy 文档的建议一致。

另见 https://mypy.readthedocs.io/en/stable/generics.html#declaring-decorators

装饰器注释

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