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import unittest
from ctypes import *
################################################################
#
# The incomplete pointer example from the tutorial
#
class MyTestCase(unittest.TestCase):
def test_incomplete_example(self):
lpcell = POINTER("cell")
class cell(Structure):
_fields_ = [("name", c_char_p),
("next", lpcell)]
SetPointerType(lpcell, cell)
c1 = cell()
c1.name = b"foo"
c2 = cell()
c2.name = b"bar"
c1.next = pointer(c2)
c2.next = pointer(c1)
p = c1
result = []
for i in range(8):
result.append(p.name)
p = p.next[0]
self.assertEqual(result, [b"foo", b"bar"] * 4)
# to not leak references, we must clean _pointer_type_cache
from ctypes import _pointer_type_cache
del _pointer_type_cache[cell]
################################################################
if __name__ == '__main__':
unittest.main()
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