如何获取方法参数名称？ [英] How to get method parameter names?

问题描述

给出Python函数：

Given the Python function:

def a_method(arg1, arg2):
    pass

如何提取参数的数量和名称。即，考虑到我对 func 的引用，我希望 func。[something] 返回（ arg1， arg2）。

How can I extract the number and names of the arguments. I.e., given that I have a reference to func, I want the func.[something] to return ("arg1", "arg2").

使用情况是我有一个装饰器，我希望以与实际函数中的键相同的顺序使用方法参数。即，当我调用 a_method（ a， b） a，b $ c>？

The usage scenario for this is that I have a decorator, and I wish to use the method arguments in the same order that they appear for the actual function as a key. I.e., how would the decorator look that printed "a,b" when I call a_method("a", "b")?

推荐答案

看看 inspect 模块-这将为您检查各种代码对象属性。

Take a look at the inspect module - this will do the inspection of the various code object properties for you.

>>> inspect.getfullargspec(a_method)
(['arg1', 'arg2'], None, None, None)

其他结果是* args和** kwargs变量的名称，以及提供的默认值。

The other results are the name of the *args and **kwargs variables, and the defaults provided. ie.

>>> def foo(a, b, c=4, *arglist, **keywords): pass
>>> inspect.getfullargspec(foo)
(['a', 'b', 'c'], 'arglist', 'keywords', (4,))

请注意，某些可调用对象在某些Python实现中可能不是自省的。例如，在CPython中，C中定义的某些内置函数不提供有关其参数的元数据。结果，如果在内置函数上使用 inspect.getfullargspec（），则将出现 ValueError 。

Note that some callables may not be introspectable in certain implementations of Python. For Example, in CPython, some built-in functions defined in C provide no metadata about their arguments. As a result, you will get a ValueError if you use inspect.getfullargspec() on a built-in function.

从Python 3.3开始，您可以使用 inspect.signature（） 来查看可调用对象的呼叫签名：

Since Python 3.3, you can use inspect.signature() to see the call signature of a callable object:

>>> inspect.signature(foo)
<Signature (a, b, c=4, *arglist, **keywords)>

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