--- a/Descriptors	Sun Jun 30 10:10:39 2013 +0200
+++ b/Descriptors	Sun Jun 30 10:11:32 2013 +0200
@@ -5,27 +5,27 @@
     for cls in self.__class__.mro():
         if name in cls.__dict__:
             attr = cls.__dict__[name]
-            if hasattr(attr, '__get__'):
+            if hasattr(attr.__class__, '__get__'):
                 return attr.__get__(self, cls)
             return attr
     return self.__getattr__(name)
 
 def set_attr(thing, name, value):
-    if hasattr(thing, '__setattr__'):
+    if hasattr(thing.__class__, '__setattr__'):
         thing.__setattr__(name, value)
         return
     for cls in self.__class__.mro():
-        if name in cls.__dict__ and hasattr(attr, '__set__'):
+        if name in cls.__dict__ and hasattr(attr.__class__, '__set__'):
             attr.__set__(self, name, value)
             return
     self.__dict__[name] = value
 
 def del_attr(thing, name):
-    if hasattr(thing, '__delattr__'):
+    if hasattr(thing.__class__, '__delattr__'):
         thing.__delattr__(name)
         return
     for cls in self.__class__.mro():
-        if name in cls.__dict__ and hasattr(attr, '__delete__'):
+        if name in cls.__dict__ and hasattr(attr.__class__, '__delete__'):
             attr.__delete__(self, name)
             return
     del self.__dict__[name]