Better way to determine if a requirement is a Permission

--HG--
branch : py3k

src/milla/auth/decorators.py

@@ -124,7 +124,7 @@ class require_perms(object):
     def __init__(self, *requirements):
         requirement = None
         for req in requirements:
-            if isinstance(req, basestring):
+            if not hasattr(req, 'check'):
                 req = permissions.Permission(req)
             if not requirement:
                 requirement = req