这是我要正确键入注释的确切函数：
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)
尽管通过mypy进行插入时没有出现任何错误,但我不确信自己做对了,也不确定如何证明这一点.
最佳答案
您的代码会进行类型检查,但可能不会执行您想要的操作,因为您将返回一个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,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.
简单策略
最简单的事情是始终要求节流阀的用户“呼叫装饰器”,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,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.
使用type.overload
如果先前的解决方案不可接受,则可以使用重载.
# Matches when we are overriding some arguments
@overload
def throttle3(_func: None = None,F]:
...
# Matches when we are not overriding any argument
@overload
def throttle3(_func: F) -> F:
...
def throttle3(
_func: Optional[F] = None,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'
您可以通过阅读its official documentation和mypy’s documentation on Function overloading了解更多有关如何使用重载的信息.