Fix mutable default arguments

make the default arguments assignment looks good.

Change-Id: I5c4a76d85d3acd5b4348ef70e593e195af4b79e1

tacker/api/api_common.py

@@ -35,8 +35,7 @@ def get_filters(request, attr_info, skips=None):
     {'check': [u'a', u'b'], 'name': [u'Bob']}
     """
     res = {}
-    if skips is None:
-        skips = []
+    skips = skips or []
     for key, values in iteritems(request.GET.dict_of_lists()):
         if key in skips:
             continue

tacker/api/v1/base.py

@@ -48,8 +48,7 @@ class Controller(object):
     def __init__(self, plugin, collection, resource, attr_info,
                  allow_bulk=False, member_actions=None, parent=None,
                  allow_pagination=False, allow_sorting=False):
-        if member_actions is None:
-            member_actions = []
+        member_actions = member_actions or []
         self._plugin = plugin
         self._collection = collection.replace('-', '_')
         self._resource = resource.replace('-', '_')

tacker/api/v1/resource_helper.py

@@ -59,8 +59,7 @@ def build_resource_info(plural_mappings, resource_map, which_service,
     resources = []
     if not which_service:
         which_service = constants.CORE
-    if action_map is None:
-        action_map = {}
+    action_map = action_map or {}
     plugin = manager.TackerManager.get_service_plugins()[which_service]
     for collection_name in resource_map:
         resource_name = plural_mappings[collection_name]

tacker/common/utils.py

@@ -252,10 +252,8 @@ def compare_elements(a, b):
 
     This method doesn't consider ordering
     """
-    if a is None:
-        a = []
-    if b is None:
-        b = []
+    a = a or []
+    b = b or []
     return set(a) == set(b)
 
 

tacker/vm/infra_drivers/heat/heat.py

@@ -207,8 +207,7 @@ class DeviceHeat(abstract_driver.DeviceAbstractDriver):
 
         def handle_port_creation(network_param, ip_list=None,
                                  mgmt_port=False):
-            if ip_list is None:
-                ip_list = []
+            ip_list = ip_list or []
             port = '%s-%s-port' % (vdu_id, network_param['network'])
             port_dict = make_port_dict()
             if mgmt_port: