Question

I’ve got a decorator function I’m applying to functions within a class. The decorator is supposed to do a check against an _api member variable. However, I get a global name 'self' is not defined error when I try to do this. What’s the right way?

def requires_api(fn):
    def wrapped(*args, **kwargs):
        if self._api is not None:
            return fn(*args, **kwargs)
        else:
            return None
    return wrapped


@requires_api       
def do_something(self):
...

Answer 1

The reference to your instance is in your wrapper function’s *args so the name self isn’t avaialble. Use args[0], or just rewrite it as:

def wrapper(self, *args, **kwargs):
    # ...

Naturally, if you do this, your call through to the wrapped function should also include self.