Question

I’m having a little problem decorating a static method in Python. I think the following code best represents my problem:

def decorator(func):
    print callable(func)
    return func

class Foo():
    @decorator
    @staticmethod
    def bar():
        return

# outputs False

print callable(Foo.bar) 
# outputs True

This seems to be a bug. I imagine it arises because when the method Foo.bar is passed to the decorator, it is a function, not a method. That is the only reason I can see for it not being callable, for if we decorate a standard function, it is not callable, as shown below.

@staticmethod
def function():
    return

print callable(function) 
# outputs False

So is this a true bug in implementation of the staticmethod decorator, and/or are there any simple workarounds? I did think of writing a decorator to asign a __call__ attribute, but I don’t know how callable is implemented, so I can’t gauge the sucess of such a method.

Answer 1

Methods are functions. But staticmethod objects aren’t. They are descriptors, so there’s extra magic that gives you a callable when you access it as Cls.static_method, but this magic can’t hide anything when you use (i.e. pass to decorator) static_method inside the body of Cls. You can’t really hack your way around this, at least not cleanly. A much simpler solution is reordering the decorators such that staticmethod get applied last – i.e. put it at the top, above all other decorators.