Is there a way to check a function's signature in Python?
<p>I'm looking for a way to check the number of arguments that a given function takes in Python.  The purpose is to achieve a more robust method of patching my classes for tests.  So, I want to do something like this:</p>

<pre><code>class MyClass (object):
    def my_function(self, arg1, arg2):
        result = ... # Something complicated
        return result

def patch(object, func_name, replacement_func):
    import new

    orig_func = getattr(object, func_name)
    replacement_func = new.instancemethod(replacement_func, 
                           object, object.__class__)

    # ...
    # Verify that orig_func and replacement_func have the 
    # same signature.  If not, raise an error.
    # ...

    setattr(object, func_name, replacement_func)

my_patched_object = MyClass()
patch(my_patched_object, "my_function", lambda self, arg1: "dummy result")
# The above line should raise an error!
</code></pre>

<p>Thanks.</p>
