How to check for a function type in Python?

Question

I've got a list of things, of which some can also be functions. If it is a function I would like to execute it. For this I do a type-check. This normally works for other types, like str, int or float. But for a function it doesn't seem to work:

>>> def f():
...     pass
... 
>>> type(f)
<type 'function'>
>>> if type(f) == function: print 'It is a function!!'
... 
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'function' is not defined
>>>

Does anybody know how I can check for a function type?

Answer 1

import types

if type(f) == types.FunctionType: 
    print 'It is a function!!'

Answer 2

Don't check types, check actions. You don't actually care if it's a function (it might be a class instance with a __call__ method, for example) - you just care if it can be called. So use callable(f).

Answer 3

collections.Callable can be used:

import collections

print isinstance(f, collections.Callable)

Answer 4

Because function isn't a built-in type, a NameError is raised. If you want to check whether something is a function, use hasattr:

>>> hasattr(f, '__call__')
True

Or you can use isinstance():

>>> from collections import Callable
>>> isinstance(f, Callable)
True
>>> isinstance(map, Callable)
True