Rebased, and fix some more copying issues

Author: WeatherGod

cycler.py

@@ -117,14 +117,18 @@ def __init__(self, left, right=None, op=None):
         if isinstance(left, Cycler):
             self._left = Cycler(left._left, left._right, left._op)
         elif left is not None:
-            self._left = list(left)
+            # Need to copy the dictionary or else that will be a residual
+            # mutable that could lead to strange errors
+            self._left = [copy.copy(v) for v in left]
         else:
             self._left = None
 
         if isinstance(right, Cycler):
             self._right = Cycler(right._left, right._right, right._op)
         elif right is not None:
-            self._right = list(right)
+            # Need to copy the dictionary or else that will be a residual
+            # mutable that could lead to strange errors
+            self._right = [copy.copy(v) for v in right]
         else:
             self._right = None
 
@@ -171,9 +175,7 @@ def change_key(self, old, new):
             # It should be completely safe at this point to
             # assume that the old key can be found in each
             # iteration.
-            for entry in self._left:
-                entry[new] = entry[old]
-                del entry[old]
+            self._left = [{new: entry[old]} for entry in self._left]
 
     def _compose(self):
         """

test_cycler.py

@@ -226,18 +226,22 @@ def test_keychange():
 
     c = c1 + c2
     c.change_key('lw', 'linewidth')
+    # Changing a key in one cycler should have no
+    # impact in the original cycler.
+    assert_equal(c2, cycler('lw', [1, 2, 3]))
     assert_equal(c, c1 + cycler('linewidth', c2))
 
     c = (c1 + c2) * c3
     c.change_key('c', 'color')
+    assert_equal(c1, cycler('c', 'rgb'))
     assert_equal(c, (cycler('color', c1) + c2) * c3)
 
     # Perfectly fine, it is a no-op
     c.change_key('color', 'color')
     assert_equal(c, (cycler('color', c1) + c2) * c3)
 
     # Can't change a key to one that is already in there
-    assert_raises(ValueError, Cycler.change_key, c, 'color', 'linewidth')
+    assert_raises(ValueError, Cycler.change_key, c, 'color', 'lw')
     # Can't change a key you don't have
     assert_raises(KeyError, Cycler.change_key, c, 'c', 'foobar')