Use only new style classes

sandbox/attributes.py

@@ -13,7 +13,7 @@ def _clear_type_cache():
 
 builtin_function = type(len)
 
-class HideAttributes:
+class HideAttributes(object):
     """
     Hide unsafe frame attributes from the Python space
     """

sandbox/recursion.py

@@ -1,7 +1,7 @@
 from __future__ import absolute_import
 import sys
 
-class SetRecursionLimit:
+class SetRecursionLimit(object):
     def __init__(self):
         self.old_limit = sys.getrecursionlimit()
 

sandbox/restorable_dict.py

@@ -1,6 +1,6 @@
 from __future__ import absolute_import
 
-class RestorableDict:
+class RestorableDict(object):
     def __init__(self, dict):
         self.dict = dict
         self.original = {}

sandbox/sandbox_class.py

@@ -17,7 +17,7 @@ def _dictProxy(data):
     for key, value in items:
         data[proxy(key)] = proxy(value)
 
-class Sandbox:
+class Sandbox(object):
     PROTECTIONS = []
 
     def __init__(self, config=None):