Move context, tidy up object model and add memory to test_rig.

volatility/framework/validity.py

@@ -10,9 +10,16 @@ class ValidityRoutines(object):
     def type_check(self, value, valid_type):
         """Checks that value is an instance of valid_type, and returns value if it is, or throws a TypeError otherwise"""
         if not isinstance(value, valid_type):
-            raise TypeError(self.__class__.__name__ + " expected " + valid_type.__class__.__name__ + ", not " + type(value))
+            print(repr(valid_type), repr(type(value).__name__))
+            raise TypeError(self.__class__.__name__ + " expected " + valid_type.__name__ + ", not " + type(value).__name__)
         return value
 
+    def class_check(self, klass, valid_class):
+        """Checks that value is an instance of valid_type, and returns value if it is, or throws a TypeError otherwise"""
+        if not issubclass(klass, valid_class):
+            raise TypeError(self.__class__.__name__ + " expected " + valid_class.__name__ + ", not " + klass.__name__)
+        return klass
+
     def confirm(self, assertion, error):
         """Acts like an assertion, but will not be disabled when __debug__ is disabled"""
         if not assertion: