How to access a caller method's __class__ attribute from a callee function in Python?

Question

Here __class__ should not be confused with self.__class__ which I am already able to access with the inspect module:

import inspect


class A:

    def __init__(self):
        print(__class__.__name__)  # I want to move this statement inside f
        f()


class B(A):
    pass


def f():
    prev_frame = inspect.currentframe().f_back
    self = prev_frame.f_locals["self"]
    print(self.__class__.__name__)


B()  # prints A B

Answer 1

The implicit __class__ reference is created at compile-time only if you actually reference it within the method (or use super). For example this code:

class Foo:
    def bar(self):
        print('bar', locals())

    def baz(self):
        print('baz', locals())

        if False:
            __class__

if __name__ == '__main__':
    foo = Foo()

    foo.bar()
    foo.baz()

Produces this output:

bar {'self': <__main__.Foo object at 0x10f45f978>}
baz {'self': <__main__.Foo object at 0x10f45f978>, '__class__': <class '__main__.Foo'>}

To find the calling function's class (in most cases) you could chain together a few CPython-specific inspect incantations:

1. Find the calling function: How to get current function into a variable?
2. Find that function's class: Get defining class of unbound method object in Python 3

I wouldn't recommend it.