Merge pull request matplotlib#3812 from jbmohler/deprecate_graylevel

API : insert deprecation warning for set_graylevel

Author: tacaswell

doc/api/api_changes/2014-11-19_remove_set_graylevel.rst

@@ -0,0 +1,6 @@
+Deprecated `GraphicsContextBase.set_graylevel`
+``````````````````````````````````````````````
+
+The `GraphicsContextBase.set_graylevel` function has been deprecated in 1.5 and
+will be removed in 1.6.  It has been unused.  The
+`GraphicsContextBase.set_foreground` could be used instead.

lib/matplotlib/backend_bases.py

@@ -1011,6 +1011,11 @@ def set_graylevel(self, frac):
         """
         Set the foreground color to be a gray level with *frac*
         """
+        # When removing, remember to remove all overrides in subclasses.
+        msg = ("set_graylevel is deprecated for removal in 1.6; "
+                "you can achieve the same result by using "
+                "set_foreground((frac, frac, frac))")
+        warnings.warn(msg, mplDeprecation)
         self._rgb = (frac, frac, frac, self._alpha)
 
     def set_joinstyle(self, js):