In Python, how can you get the name of a member function's class?

Question

I have a function that takes another function as a parameter. If the function is a member of a class, I need to find the name of that class. E.g.

def analyser(testFunc):
    print testFunc.__name__, 'belongs to the class, ...

I thought

testFunc.__class__

would solve my problems, but that just tells me that testFunc is a function.

Answer 1

I'm not a Python expert, but does this work?

testFunc.__self__.__class__

It seems to work for bound methods, but in your case, you may be using an unbound method, in which case this may work better:

testFunc.__objclass__

Here's the test I used:

Python 2.5.2 (r252:60911, Jul 31 2008, 17:31:22) 
[GCC 4.2.3 (Ubuntu 4.2.3-2ubuntu7)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import hashlib
>>> hd = hashlib.md5().hexdigest
>>> hd
<built-in method hexdigest of _hashlib.HASH object at 0x7f9492d96960>
>>> hd.__self__.__class__
<type '_hashlib.HASH'>
>>> hd2 = hd.__self__.__class__.hexdigest
>>> hd2
<method 'hexdigest' of '_hashlib.HASH' objects>
>>> hd2.__objclass__
<type '_hashlib.HASH'>

Oh yes, another thing:

>>> hd.im_class
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'builtin_function_or_method' object has no attribute 'im_class'
>>> hd2.im_class
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'method_descriptor' object has no attribute 'im_class'

So if you want something bulletproof, it should handle __objclass__ and __self__ too. But your mileage may vary.

Answer 2

testFunc.im_class

http://www.python.org/doc/2.5.2/ref/types.html

im_class is the class of im_self for bound methods or the class that asked for the method for unbound methods

Answer 3

instance methods will have attributes .im_class .im_func .im_self

http://docs.python.org/library/inspect.html#types-and-members

You probably want to see if the function hasattr .im_class, and get the class info from there.