BUG/API : fix color validation

tacaswell · tacaswell · commit ff99a043a687 · 2015-03-13T21:51:24.000-04:00
Possible fix for #4192. This adds a new validation (validate_color_or_None) method for color which allows None and restores `validate_color` to fail on None. This will allow selected color rcparams to be `None` (not `'None'`) which the library should interpret as "don't use this rcparam".
diff --git a/lib/matplotlib/rcsetup.py b/lib/matplotlib/rcsetup.py
@@ -235,18 +235,31 @@ 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
+    return validate_color(s)
+
+
 def validate_color(s):
     'return a valid color arg'
-    if s in (None, 'none', 'None'):
-        return None
+    if s is None:
+        raise ValueError('%s does not look like a color arg' % (s, ))
 
     if is_color_like(s):
         return s
 
     stmp = '#' + s
+
     if is_color_like(stmp):
         return stmp
 
+    try:
+        if s.lower() == 'none':
+            return 'None'
+    except AttributeError:
+        pass
+
     # If it is still valid, it must be a tuple.
     colorarg = s
     msg = ''
@@ -685,9 +698,8 @@ 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], # background color; white
-    'legend.edgecolor': [None, validate_color], # edge color; black
-
+    'legend.facecolor': [None, validate_color_or_None],
+    'legend.edgecolor': [None, validate_color_or_None],
 
     ## tick properties
     'xtick.major.size':  [4, validate_float],    # major xtick size in points
