__all__ = ['dictproxy', 'make_dictproxy']
from ctypes import pythonapi, py_object
from _ctypes import PyObj_FromPtr
PyDictProxy_New = pythonapi.PyDictProxy_New
PyDictProxy_New.argtypes = (py_object,)
PyDictProxy_New.rettype = py_object
def make_dictproxy(obj):
assert isinstance(obj,dict)
return PyObj_FromPtr(PyDictProxy_New(obj))
## make_dictproxy = lambda dictobj: type('',(),dictobj).__dict__
# for isinstance() check
dictproxy = type(make_dictproxy({}))
if __name__ == '__main__':
import unittest
class DictProxyTestCase(unittest.TestCase):
def test_instance(self):
d = make_dictproxy({})
self.assertTrue(isinstance(d,dictproxy))
self.assertFalse(isinstance(d.copy(),dictproxy))
def test_get(self):
d = make_dictproxy({'a': 'b', 'c': 'd'})
self.assertEqual('b', d.get('a'))
self.assertEqual('d', d.get('c'))
def test_set(self):
d = make_dictproxy({})
def _test_item_assignment():
d['a'] = 10
self.assertRaises(TypeError, _test_item_assignment)
def test_copy(self):
d1 = make_dictproxy({'a': 'b', 'c': 'd'})
d2 = d1.copy()
self.assertEqual(d1, d2)
self.assertTrue(isinstance(d2,dict))
d2['a'] = 'z'
self.assertNotEqual(d1, d2)
self.assertEqual('z', d2['a'])
def test_not_immutable(self):
a = dict(val=20)
b = make_dictproxy(a)
a['val'] = 10
self.assertEqual(10, b['val'])
# This is ok, correct behavior.
# So ... can/should not use dictproxy as immutable dict.
# dictproxy just hide the interface.
unittest.main()
