MNT : try to fix optional/inherited rcparams

tacaswell · tacaswell · commit 636003af4cd9 · 2015-03-13T21:47:53.000-04:00
Attempt to implement 'inherited' rcparams, that is rcparams that are only used if they are non-default. Re-introduces feature introduced in #3792 /92e608d655f1fa667fdf5bc3e99f950eb08f7c42 and reverted in c90469b
diff --git a/lib/matplotlib/legend.py b/lib/matplotlib/legend.py
@@ -346,12 +346,12 @@ def __init__(self, parent, handles, labels,
         # We use FancyBboxPatch to draw a legend frame. The location
         # and size of the box will be updated during the drawing time.
 
-        if rcParams["legend.facecolor"] is None:
+        if rcParams["legend.facecolor"] == 'inherit':
             facecolor = rcParams["axes.facecolor"]
         else:
             facecolor = rcParams["legend.facecolor"]
 
-        if rcParams["legend.edgecolor"] is None:
+        if rcParams["legend.edgecolor"] == 'inherit':
             edgecolor = rcParams["axes.edgecolor"]
         else:
             edgecolor = rcParams["legend.edgecolor"]
diff --git a/lib/matplotlib/rcsetup.py b/lib/matplotlib/rcsetup.py
@@ -225,17 +225,14 @@ def __call__(self, s):
             raise ValueError('Could not convert all entries to ints')
 
 
-def validate_color_or_None(s):
-    if s is None:
-        return None
+def validate_color_or_inherit(s):
+    'return a valid color arg'
+    if s == 'inherit':
+        return s
     return validate_color(s)
 
 
 def validate_color(s):
-    'return a valid color arg'
-    if s is None:
-        raise ValueError('%s does not look like a color arg' % (s, ))
-
     if is_color_like(s):
         return s
 
@@ -674,8 +671,8 @@ def __call__(self, s):
     # the relative size of legend markers vs. original
     'legend.markerscale': [1.0, validate_float],
     'legend.shadow': [False, validate_bool],
-    'legend.facecolor': [None, validate_color_or_None],
-    'legend.edgecolor': [None, validate_color_or_None],
+    'legend.facecolor': ['inherit', validate_color_or_inherit],
+    'legend.edgecolor': ['inherit', validate_color_or_inherit],
 
     ## tick properties
     'xtick.major.size':  [4, validate_float],    # major xtick size in points
