import ctypes

import unittest

import warnings

from ctypes import Structure, POINTER, pointer, c_char_p

# String-based "incomplete pointers" were implemented in ctypes 0.6.3 (2003, when

# ctypes was an external project). They made obsolete by the current

# incomplete *types* (setting `_fields_` late) in 0.9.5 (2005).

# ctypes was added to Python 2.5 (2006), without any mention in docs.

# This tests incomplete pointer example from the old tutorial

# (https://svn.python.org/projects/ctypes/tags/release_0_6_3/ctypes/docs/tutorial.stx)

class TestSetPointerType(unittest.TestCase):

def tearDown(self):

ctypes._pointer_type_cache_fallback.clear()

def test_incomplete_example(self):

with self.assertWarns(DeprecationWarning):

lpcell = POINTER("cell")

class cell(Structure):

_fields_ = [("name", c_char_p),

("next", lpcell)]

with warnings.catch_warnings():

warnings.simplefilter('ignore', DeprecationWarning)

ctypes.SetPointerType(lpcell, cell)

self.assertIs(POINTER(cell), lpcell)

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)

def test_deprecation(self):

with self.assertWarns(DeprecationWarning):

lpcell = POINTER("cell")

class cell(Structure):

_fields_ = [("name", c_char_p),

("next", lpcell)]

with self.assertWarns(DeprecationWarning):

ctypes.SetPointerType(lpcell, cell)

self.assertIs(POINTER(cell), lpcell)

if __name__ == '__main__':

unittest.main()