How to use ctypes to call a DLL function with double underline function name?

The function can be called with the following syntax as well, and bypasses the obfuscation Python applies to "dunder" attributes of class instances:

self.windll['__apiJob']()

Example below:

test.cpp

extern "C" __declspec(dllexport)
int __apiJob() {
    return 123;
}

test.py

import ctypes

class Job:

    def __init__(self):
        dll = ctypes.CDLL('./test')
        self.apiJob = dll['__apiJob'] # bypass "dunder" class name mangling
        self.apiJob.argtypes = ()
        self.apiJob.restype = ctypes.c_int

    def execute(self):
        return self.apiJob()

a = Job()
result = a.execute()
print(result)

Output:

123

As an aside, WinDLL is used for DLLs declaring functions using __stdcall calling convention in 32-bit DLLs. CDLL is used for the default __cdecl calling convention. 64-bit DLLs have only one calling convention, so either works, but for portability keep this in mind.