How to check if a function exist (but not inherited) in python?

Question

Kind of related to this question:

https://stackoverflow.com/questions/8708525/how-to-check-if-mako-function-exist

I want to check if a function exists for a given class, but not inherited, so that the parent can called the child's function, since otherwise it would result in an infinite recursion..

edit:

it actually gives a maximum stack level error, which is the same.

the equivalent code would be:

class A(object):
    def f(x):
        b = B()
        b.f()

class B(A):
    pass

a = A()
a.f()

i understand this is not clean or preferred, but it is what the template translates to, and I dunno how to check for it otherwise.

Answer 1

I want to check if a function exists for a given class, but not inherited

Yes, you can check the class dictionary directly. Either use the __dict__ attribute or the built-in vars() function::

>>> class A(object):
        def f(x):
            pass

>>> class B(A):
        def g(x):
            pass

>>> 'f' in vars(B)
False
>>> 'g' in vars(B)
True

Answer 2

If what you need is to check whether the method is defined directly in instance's class and not in one of its ancestors then you can try this:

import inspect

def has_method(obj, name):
    v = vars(obj.__class__)
    # check if name is defined in obj's class and that name is a method
    return name in v and inspect.isroutine(v[name])

class A:
    def foo(self):
        print 'foo'

class B(A):
    pass

b = B()
a = A()

print has_method(a, 'foo') # => True
print has_method(b, 'foo') # => False