1from ctypes import *
2import unittest
3
4class X(Structure):
5    _fields_ = [("a", c_int),
6                ("b", c_int)]
7    new_was_called = False
8
9    def __new__(cls):
10        result = super(X, cls).__new__(cls)
11        result.new_was_called = True
12        return result
13
14    def __init__(self):
15        self.a = 9
16        self.b = 12
17
18class Y(Structure):
19    _fields_ = [("x", X)]
20
21
22class InitTest(unittest.TestCase):
23    def test_get(self):
24        # make sure the only accessing a nested structure
25        # doesn't call the structure's __new__ and __init__
26        y = Y()
27        self.assertEqual((y.x.a, y.x.b), (0, 0))
28        self.assertEqual(y.x.new_was_called, False)
29
30        # But explicitly creating an X structure calls __new__ and __init__, of course.
31        x = X()
32        self.assertEqual((x.a, x.b), (9, 12))
33        self.assertEqual(x.new_was_called, True)
34
35        y.x = x
36        self.assertEqual((y.x.a, y.x.b), (9, 12))
37        self.assertEqual(y.x.new_was_called, False)
38
39if __name__ == "__main__":
40    unittest.main()
41