import inspect
inspect.getargspec(someMethod)

查看inspect模块

假设您可能正在处理基于类的方法或简单的函数，您可以像下面这样做。

如果输入是类方法(因此包括self)，这将自动减去一个输入。

import types
def get_arg_count(fn):
    extra_method_input_count=1 if isinstance(fn, types.MethodType) else 0
    return fn.__code__.co_argcount-extra_method_input_count

然后你可以根据需要应用到函数或方法:

def fn1(a, b, c):
    return None

class cl1:
    def fn2(self, a, b, c):
        return None

print(get_arg_count(fn1)) #=> 3
print(get_arg_count(cl1().fn2)) #=> 3

import inspect
inspect.getargspec(someMethod)

查看inspect模块

inspect.getargspec ()

Get the names and default values of a function’s arguments. A tuple of four things is returned: (args, varargs, varkw, defaults). args is a list of the argument names (it may contain nested lists). varargs and varkw are the names of the * and ** arguments or None. defaults is a tuple of default argument values or None if there are no default arguments; if this tuple has n elements, they correspond to the last n elements listed in args. Changed in version 2.6: Returns a named tuple ArgSpec(args, varargs, keywords, defaults).

看到can-you-list-the-keyword-arguments-a-python-function-receives。

func.__code__。co_argcount给出了在*args之前任何参数的个数

函数。__kwdefaults__给你一个字典的关键字参数AFTER *args

func.__code__。Co_kwonlyargcount等于len(funct .__kwdefaults__)

函数。__defaults__提供了出现在*args之前的可选参数值

这里有一个简单的例子:

>>> def a(b, c, d, e, f=1, g=3, h=None, *i, j=2, k=3, **L):
    pass

>>> a.__code__.co_argcount
7
>>> a.__defaults__
(1, 3, None)
>>> len(a.__defaults__)
3
>>> 
>>> 
>>> a.__kwdefaults__
{'j': 2, 'k': 3}
>>> len(a.__kwdefaults__)
2
>>> a.__code__.co_kwonlyargcount
2

Inspect.getargspec()来满足您的需求

from inspect import getargspec

def func(a, b):
    pass
print len(getargspec(func).args)