python - how to reference Class declared inside a function

Question

There is a Class from a third party lib I am using.

def funcA(base):
    class ClassA(base):
        def __init__(self, obj):
        ....

I have an instance of ClassA a

type(a)

# prints <class 'path.to.module.funcA.<locals>.ClassA'>

How can I check if a variable is an instance of ClassA? I am not sure how to reference ClassA since it is under a function....

import module
isinstance(a, module.funcA.ClassA?) <--- how to reference ClassA?

Answer 1

If you are not able to change funcA itself because it's not in your own code, then a neat way to test for instances is to give it a superclass and test for the superclass. Replace funcA with a wrapped version, which calls the original funcA with a class that extends both base and your own ClassABase :

import functools

class ClassABase:
    pass

def funcAwrapper(f):
    @functools.wraps(f)
    def wrapper(base):
        class WrappedBase(base, ClassABase):
            pass
        return f(WrappedBase)
    return wrapper

funcA = funcAwrapper(funcA)

Now all of the instances of ClassA created by funcA will also be instances of your own ClassABase , so you can test isinstance(obj, ClassABase) .