def test_ref(self):
a = ref(symbol('a'))
self.assertEqual(deref(a), undefined)
self.assertEqual(setref(a, 100), 100)
self.assertEqual(deref(a), 100)
self.assertEqual(repr(a), "ref(symbol('a'))")
b = ref(symbol('b'), 101)
self.assertEqual(deref(b), 101)
def test_attr(self):
a = ref(symbol('a'))
b = attr(symbol('b'), a._get_value, a._set_value)
self.assertEqual(deref(a), deref(b))
self.assertEqual(deref(b), undefined)
self.assertEqual(setref(b, 101), 101)
self.assertEqual(deref(b), 101)
self.assertEqual(deref(a), 101)
self.assertEqual(setref(a, 102), 102)
self.assertEqual(deref(b), 102)
self.assertEqual(deref(a), 102)
c = attr(symbol('c'), a._get_value)
self.assertEqual(deref(c), 102)
with self.assertRaises(AttributeError):
setref(c, 999)
