from ctypes import Structure, c_void_p

class FSCRT():
    class FONT(Structure):
        _fields_ = [('pData', c_void_p),]
        def __del__(self):
            print("font release")
fscrt = FSCRT()

class FSPDF():
    class TEXTSTATE(Structure):
        _fields_ = [("font", fscrt.FONT),]
        def __str__(self):
            return "TEXTSTATE {font: %s}" % self.font
fspdf = FSPDF()

state = fspdf.TEXTSTATE()
state.font = fscrt.FONT()
input(state)

-------OUTPUT-------
font release
font release
TEXTSTATE {font: <__main__.FSCRT.FONT object at 0x0000000002AD1BC8>}