from ctypes import Structure, c_void_p
class FONT(Structure):
    _fields_ = [('pData', c_void_p),]
    def __del__(self): print("release font", self)
class SETTINGS(Structure):
    _fields_ = [("font", FONT),]
def setFont():
    settings = SETTINGS()
    f = FONT()
    settings.font = f
    print(settings.font)
    print(settings)
setFont()


----------------------
<__main__.FONT object at 0x0000000004495948>
release font <__main__.FONT object at 0x0000000004495948>
<__main__.SETTINGS object at 0x00000000044958C8>
release font <__main__.FONT object at 0x0000000004495848>