small error handling change

jaredly · Jun 19, 2010 · b0d0e6f · b0d0e6f
1 parent b4dc2db
commit b0d0e6f
Showing 1 changed file with 3 additions and 1 deletion.
diff --git a/clevercss/engine.py b/clevercss/engine.py
@@ -27,8 +27,10 @@ def __init__(self, source, parser=None, fname=None):
     def evaluate(self, context=None):
         """Evaluate code."""
         expr = None
-        if not isinstance(context, dict): 
+        if context is None:
             context = {}
+        elif not isinstance(context, dict): 
+            raise TypeError("context argument must be a dictionary")
 
         for key, value in context.iteritems():
             if isinstance(value, str):