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import unittest
from ctypes import *
class StructFieldsTestCase(unittest.TestCase):
# Structure/Union classes must get 'finalized' sooner or
# later, when one of these things happen:
#
# 1. _fields_ is set.
# 2. An instance is created.
# 3. The type is used as field of another Structure/Union.
# 4. The type is subclassed
#
# When they are finalized, assigning _fields_ is no longer allowed.
def test_1_A(self):
class X(Structure):
pass
self.assertEqual(sizeof(X), 0) # not finalized
X._fields_ = [] # finalized
self.assertRaises(AttributeError, setattr, X, "_fields_", [])
def test_1_B(self):
class X(Structure):
_fields_ = [] # finalized
self.assertRaises(AttributeError, setattr, X, "_fields_", [])
def test_2(self):
class X(Structure):
pass
X()
self.assertRaises(AttributeError, setattr, X, "_fields_", [])
def test_3(self):
class X(Structure):
pass
class Y(Structure):
_fields_ = [("x", X)] # finalizes X
self.assertRaises(AttributeError, setattr, X, "_fields_", [])
def test_4(self):
class X(Structure):
pass
class Y(X):
pass
self.assertRaises(AttributeError, setattr, X, "_fields_", [])
Y._fields_ = []
self.assertRaises(AttributeError, setattr, X, "_fields_", [])
if __name__ == "__main__":
unittest.main()
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