这是我要正确键入注释的确切功能:
F = TypeVar('F', bound=Callable[..., Any])
def throtle(_func: Optional[F] = None, *, rate: float = 1) -> Union[F, Callable[[F], F]]:
"""Throtles a function call, so that at minimum it can be called every `rate` seconds.
Usage::
# this will enforce the default minimum time of 1 second between function calls
@throtle
def ...
or::
# this will enforce a custom minimum time of 2.5 seconds between function calls
@throtle(rate=2.5)
def ...
This will raise an error, because `rate=` needs to be specified::
@throtle(5)
def ...
"""
def decorator(func: F) -> F:
@functools.wraps(func)
def wrapper(*args: Any, **kwargs: Any) -> Any:
time.sleep(rate)
return func(*args, **kwargs)
return cast(F, wrapper)
if _func is None:
return decorator
else:
return decorator(_func)
虽然通过mypy进行插入时没有出现任何错误,但我不相信自己做的正确,也不确定如何进行验证。
答案 0 :(得分:2)
您的代码进行类型检查,但可能不会执行您想要的操作,因为您返回的是Union
。
要检查mypy推断某个变量的类型,可以使用reveal_type
。
# Note: I am assuming you meant "throttle" and so I changed your spelling
def throttle1(
_func: Optional[F] = None, *, rate: float = 1.0
) -> Union[F, Callable[[F], F]]:
# code omitted
@throttle1
def hello1() -> int:
return 42
reveal_type(hello1) # Revealed type is 'Union[def () -> builtins.int, def (def () -> builtins.int) -> def () -> builtins.int]'
假设我们希望hello1
是一个返回int的函数(即def () -> builtins.int
),我们需要尝试其他方法。
最简单的方法是始终要求throttle
的用户“呼叫装饰者”,即使她/他没有重写任何参数也是如此:
def throttle2(*, rate: float = 1.0) -> Callable[[F], F]:
def decorator(func: F) -> F:
@functools.wraps(func)
def wrapper(*args: Any, **kwargs: Any) -> Any:
time.sleep(rate)
return func(*args, **kwargs)
return cast(F, wrapper)
return decorator
@throttle2() # Note that I am calling throttle2 without arguments
def hello2() -> int:
return 42
reveal_type(hello2) # Revealed type is 'def () -> builtins.int'
@throttle2(rate=2.0)
def hello3() -> int:
return 42
reveal_type(hello3) # Revealed type is 'def () -> builtins.int'
这已经有效并且非常简单。
typing.overload
如果先前的解决方案不可接受,则可以使用overload
。
# Matches when we are overriding some arguments
@overload
def throttle3(_func: None = None, *, rate: float = 1.0) -> Callable[[F], F]:
...
# Matches when we are not overriding any argument
@overload
def throttle3(_func: F) -> F:
...
def throttle3(
_func: Optional[F] = None, *, rate: float = 1.0
) -> Union[F, Callable[[F], F]]:
# your original code goes here
@throttle3 # Note: we do not need to call the decorator
def hello4() -> int:
return 42
reveal_type(hello4) # Revealed type is 'def () -> builtins.int'
@throttle3(rate=2.0)
def hello5() -> int:
return 42
reveal_type(hello5) # Revealed type is 'def () -> builtins.int'
通过阅读its official documentation和mypy's documentation on Function overloading,您可以了解更多有关如何使用overload
的信息。