newrange: added attr read-only properties

Author: Brad Walker

src/future/types/newrange.py

@@ -55,6 +55,18 @@ def __init__(self, *args):
         self._step = step
         self._len = (stop - start) // step + bool((stop - start) % step)
 
+    @property
+    def start(self):
+        return self._start
+
+    @property
+    def stop(self):
+        return self._stop
+
+    @property
+    def step(self):
+        return self._step
+
     def __repr__(self):
         if self._step == 1:
             return 'range(%d, %d)' % (self._start, self._stop)

tests/test_future/test_range.py

@@ -99,6 +99,16 @@ def test_slice_zero_step(self):
         with self.assertRaisesRegexp(ValueError, msg):
             range(8)[::0]
 
+    def test_properties(self):
+        # Exception string differs between PY2/3
+        r = range(0)
+        with self.assertRaises(AttributeError):
+            r.start = 0
+        with self.assertRaises(AttributeError):
+            r.stop = 0
+        with self.assertRaises(AttributeError):
+            r.step = 0
+
 
 if __name__ == '__main__':
     unittest.main()