For collections.deque() objects, expose the maxlen parameter as a read-only attribute.
diff --git a/Lib/test/test_deque.py b/Lib/test/test_deque.py
index a9e010e..fab5a7c 100644
--- a/Lib/test/test_deque.py
+++ b/Lib/test/test_deque.py
@@ -105,6 +105,16 @@
d.extendleft(it)
self.assertEqual(list(it), [])
+ def test_maxlen_attribute(self):
+ self.assertEqual(deque().maxlen, None)
+ self.assertEqual(deque('abc').maxlen, None)
+ self.assertEqual(deque('abc', maxlen=4).maxlen, 4)
+ self.assertEqual(deque('abc', maxlen=2).maxlen, 2)
+ self.assertEqual(deque('abc', maxlen=0).maxlen, 0)
+ with self.assertRaises(AttributeError):
+ d = deque('abc')
+ d.maxlen = 10
+
def test_comparisons(self):
d = deque('xabc'); d.popleft()
for e in [d, deque('abc'), deque('ab'), deque(), list(d)]: