Merge pull request #3196 from astrofrog/issue-3196

mdboom · mdboom · commit d99eb8667185 · 2014-12-03T12:34:55.000-05:00
Issue with iterability of axes arguments [backport to 1.4.x]
diff --git a/lib/matplotlib/figure.py b/lib/matplotlib/figure.py
@@ -780,8 +780,14 @@ def fixitems(items):
             # to tuples for the key
             ret = []
             for k, v in items:
-                if iterable(v):
+                # some objects can define __getitem__ without being
+                # iterable and in those cases the conversion to tuples
+                # will fail. So instead of using the iterable(v) function
+                # we simply try and convert to a tuple, and proceed if not.
+                try:
                     v = tuple(v)
+                except Exception:
+                    pass
                 ret.append((k, v))
             return tuple(ret)
 
diff --git a/lib/matplotlib/tests/test_figure.py b/lib/matplotlib/tests/test_figure.py
@@ -6,6 +6,7 @@
 
 from nose.tools import assert_equal, assert_true, assert_raises
 from matplotlib.testing.decorators import image_comparison, cleanup
+from matplotlib.axes import Axes
 import matplotlib.pyplot as plt
 
 
@@ -110,6 +111,36 @@ def test_too_many_figures():
     assert len(w) == 1
 
 
+def test_iterability_axes_argument():
+
+    # This is a regression test for matplotlib/matplotlib#3196. If one of the
+    # arguments returned by _as_mpl_axes defines __getitem__ but is not
+    # iterable, this would raise an execption. This is because we check
+    # whether the arguments are iterable, and if so we try and convert them
+    # to a tuple. However, the ``iterable`` function returns True if
+    # __getitem__ is present, but some classes can define __getitem__ without
+    # being iterable. The tuple conversion is now done in a try...except in
+    # case it fails.
+
+    class MyAxes(Axes):
+        def __init__(self, *args, **kwargs):
+            kwargs.pop('myclass', None)
+            return Axes.__init__(self, *args, **kwargs)
+
+    class MyClass(object):
+
+        def __getitem__(self, item):
+            if item != 'a':
+                raise ValueError("item should be a")
+
+        def _as_mpl_axes(self):
+            return MyAxes, {'myclass': self}
+
+    fig = plt.figure()
+    ax = fig.add_subplot(1, 1, 1, projection=MyClass())
+    plt.close(fig)
+
+
 if __name__ == "__main__":
     import nose
     nose.runmodule(argv=['-s', '--with-doctest'], exit=False)
