Lib/ctypes/test/test_init.py

   1 from ctypes import *
   2 import unittest
   3
   4 class 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
  18 class Y(Structure):
  19     _fields_ = [("x", X)]
  20
  21
  22 class 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 explicitely 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
  39 if __name__ == "__main__":
  40     unittest.main()