Use six.add_metaclass instead of __metaclass__

According to http://docs.openstack.org/developer/hacking/ it should
be preferred to use six.add_metaclass instead of __metaclass__.

Change-Id: Iec6550421bcf54f30952d9dc9f3a398288d6a283

horizon/tables/actions.py

@@ -24,6 +24,7 @@ from django.utils.functional import Promise  # noqa
 from django.utils.http import urlencode  # noqa
 from django.utils.translation import pgettext_lazy
 from django.utils.translation import ugettext_lazy as _
+import six
 
 from horizon import exceptions
 from horizon import messages
@@ -80,9 +81,9 @@ class BaseActionMetaClass(type):
         return klass
 
 
+@six.add_metaclass(BaseActionMetaClass)
 class BaseAction(html.HTMLElement):
     """Common base class for all ``Action`` classes."""
-    __metaclass__ = BaseActionMetaClass
 
     def __init__(self, **kwargs):
         super(BaseAction, self).__init__()

horizon/tables/base.py

@@ -33,6 +33,7 @@ from django.utils.http import urlencode
 from django.utils.safestring import mark_safe
 from django.utils import termcolors
 from django.utils.translation import ugettext_lazy as _
+import six
 
 from horizon import conf
 from horizon import exceptions
@@ -1015,6 +1016,7 @@ class DataTableMetaclass(type):
         return type.__new__(mcs, name, bases, attrs)
 
 
+@six.add_metaclass(DataTableMetaclass)
 class DataTable(object):
     """A class which defines a table with all data and associated actions.
 
@@ -1039,7 +1041,6 @@ class DataTable(object):
         :class:`~horizon.tables.FilterAction` class (if one is provided)
         using the current request's query parameters.
     """
-    __metaclass__ = DataTableMetaclass
 
     def __init__(self, request, data=None, needs_form_wrapper=None, **kwargs):
         self.request = request

horizon/workflows/base.py

@@ -26,6 +26,7 @@ from django.template.defaultfilters import slugify  # noqa
 from django.utils.encoding import force_unicode
 from django.utils.importlib import import_module  # noqa
 from django.utils.translation import ugettext_lazy as _
+import six
 
 from horizon import base
 from horizon import exceptions
@@ -73,6 +74,7 @@ class ActionMetaclass(forms.forms.DeclarativeFieldsMetaclass):
         return cls
 
 
+@six.add_metaclass(ActionMetaclass)
 class Action(forms.Form):
     """An ``Action`` represents an atomic logical interaction you can have with
     the system. This is easier to understand with a conceptual example: in the
@@ -123,8 +125,6 @@ class Action(forms.Form):
         customize your help text template to display practically anything.
     """
 
-    __metaclass__ = ActionMetaclass
-
     def __init__(self, request, context, *args, **kwargs):
         if request.method == "POST":
             super(Action, self).__init__(request.POST, initial=context)
@@ -484,6 +484,7 @@ class UpdateMembersStep(Step):
             return self.slug + "_role_" + role_id
 
 
+@six.add_metaclass(WorkflowMetaclass)
 class Workflow(html.HTMLElement):
     """A Workflow is a collection of Steps. Its interface is very
     straightforward, but it is responsible for handling some very
@@ -587,7 +588,6 @@ class Workflow(html.HTMLElement):
         Defaults to ``False``.
 
     """
-    __metaclass__ = WorkflowMetaclass
     slug = None
     default_steps = ()
     template_name = "horizon/common/_workflow.html"

openstack_dashboard/api/network_base.py

@@ -21,7 +21,10 @@ methods defined in this module.
 
 import abc
 
+import six
 
+
+@six.add_metaclass(abc.ABCMeta)
 class FloatingIpManager(object):
     """Abstract class to implement Floating IP methods
 
@@ -37,8 +40,6 @@ class FloatingIpManager(object):
     * instance_id: Instance ID of an associated with the Floating IP
     """
 
-    __metaclass__ = abc.ABCMeta
-
     @abc.abstractmethod
     def list_pools(self):
         """Fetches a list of all floating IP pools.
@@ -129,6 +130,7 @@ class FloatingIpManager(object):
         pass
 
 
+@six.add_metaclass(abc.ABCMeta)
 class SecurityGroupManager(object):
     """Abstract class to implement Security Group methods
 
@@ -159,8 +161,6 @@ class SecurityGroupManager(object):
 
     """
 
-    __metaclass__ = abc.ABCMeta
-
     @abc.abstractmethod
     def list(self):
         """Fetches a list all security groups.

tox.ini

@@ -60,6 +60,7 @@ exclude = .venv,.git,.tox,dist,*openstack/common*,*lib/python*,*egg,build,panel_
 # H702 Formatting operation should be outside of localization method call
 # H803 git commit title should not end with period (disabled on purpose, see bug #1236621)
 ignore = E127,E128,H701,H702,H803
+select = H236
 
 [hacking]
 import_exceptions = collections.defaultdict,