如何在装饰器中获取参数类型提示？

Question

如何执行以下操作：

import typing

def needs_parameter_type(decorated):
    def decorator(*args):
        [do something with the *type* of bar (aka args[0]), some_class]
        decorated(*args)
    return decorator

@needs_parameter_type
def foo(bar: SomeClass):
    …

foo(…)

用例是为了避免以下重复：

@needs_parameter_type(SomeClass)
def foo(bar: SomeClass):
    …

Answer 1

这些存储在函数的__annotations__属性中，您可以通过以下方式访问它们：

def needs_parameter_type(decorated):
    def decorator(*args):
        print(decorated.__annotations__)
        decorated(*args)
    return decorator

@needs_parameter_type
def foo(bar: int):
   pass

foo(1)
#  {"bar": <class "int">}