PEP8 type comparison cleanup

Fixes bug #910295

The None, True, and False values are singletons.

All variable *comparisons* to singletons should use 'is' or 'is not'.
All variable *evaluations* to boolean should use 'if' or 'if not'.

"== None", "== True", "== False", and "!= None" comparisons in sqlalchemy's
where(), or_(), filter(), and_(), and select() functions should not be changed.

Incorrect comparisons or evaluations in comments were not changed.

Change-Id: I087f0883bf115b5fe714ccfda86a794b9b2a87f7

bin/nova-manage

@@ -1605,7 +1605,7 @@ class VsaDriveTypeCommands(object):
         if name is not None:
             search_opts['extra_specs']['name'] = name
 
-        if all == False:
+        if not all:
             search_opts['extra_specs']['visible'] = '1'
 
         drives = volume_types.get_all_types(self.context,
@@ -1973,7 +1973,7 @@ class StorageManagerCommands(object):
         ctxt = context.get_admin_context()
 
         try:
-            if flavor == None:
+            if flavor is None:
                 flavors = db.sm_flavor_get_all(ctxt)
             else:
                 flavors = db.sm_flavor_get(ctxt, flavor)
@@ -2015,7 +2015,7 @@ class StorageManagerCommands(object):
         ctxt = context.get_admin_context()
 
         try:
-            if backend_conf_id == None:
+            if backend_conf_id is None:
                 backends = db.sm_backend_conf_get_all(ctxt)
             else:
                 backends = db.sm_backend_conf_get(ctxt, backend_conf_id)
@@ -2075,7 +2075,7 @@ class StorageManagerCommands(object):
         print '(WARNING: Creating will destroy all data on backend!!!)'
         c = raw_input('Proceed? (y/n) ')
         if c == 'y' or c == 'Y':
-            if flavor_label == None:
+            if flavor_label is None:
                 print "error: backend needs to be associated with flavor"
                 sys.exit(2)
 

nova/common/cfg.py

@@ -821,7 +821,7 @@ class ConfigOpts(object):
         :return: False if the opt was already register, True otherwise
         :raises: DuplicateOptError, ArgsAlreadyParsedError
         """
-        if self._args != None:
+        if self._args is not None:
             raise ArgsAlreadyParsedError("cannot register CLI option")
 
         if not self.register_opt(opt, group):

nova/scheduler/vsa.py

@@ -130,8 +130,7 @@ class VsaScheduler(simple.SimpleScheduler):
         return filtered_hosts
 
     def _allowed_to_use_host(self, host, selected_hosts, unique):
-        if unique == False or \
-           host not in [item[0] for item in selected_hosts]:
+        if not unique or host not in [item[0] for item in selected_hosts]:
             return True
         else:
             return False

nova/tests/scheduler/test_distributed_scheduler.py

@@ -236,11 +236,11 @@ class DistributedSchedulerTestCase(test.TestCase):
         for weighted_host in weighted_hosts:
             # We set this up so remote hosts have even weights ...
             if int(weighted_host.weight) % 2 == 0:
-                self.assertTrue(weighted_host.zone != None)
-                self.assertTrue(weighted_host.host == None)
+                self.assertTrue(weighted_host.zone is not None)
+                self.assertTrue(weighted_host.host is None)
             else:
-                self.assertTrue(weighted_host.host != None)
-                self.assertTrue(weighted_host.zone == None)
+                self.assertTrue(weighted_host.host is not None)
+                self.assertTrue(weighted_host.zone is None)
 
     def test_schedule_local_zone(self):
         """Test to make sure _schedule makes no call out to zones if
@@ -270,8 +270,8 @@ class DistributedSchedulerTestCase(test.TestCase):
         self.assertEquals(len(weighted_hosts), 10)
         for weighted_host in weighted_hosts:
             # There should be no remote hosts
-            self.assertTrue(weighted_host.host != None)
-            self.assertTrue(weighted_host.zone == None)
+            self.assertTrue(weighted_host.host is not None)
+            self.assertTrue(weighted_host.zone is None)
 
     def test_decrypt_blob(self):
         """Test that the decrypt method works."""

nova/vsa/api.py

@@ -68,10 +68,10 @@ class API(base.Base):
         super(API, self).__init__(**kwargs)
 
     def _check_volume_type_correctness(self, vol_type):
-        if vol_type.get('extra_specs') == None or\
+        if vol_type.get('extra_specs') is None or\
            vol_type['extra_specs'].get('type') != 'vsa_drive' or\
-           vol_type['extra_specs'].get('drive_type') == None or\
-           vol_type['extra_specs'].get('drive_size') == None:
+           vol_type['extra_specs'].get('drive_type') is None or\
+           vol_type['extra_specs'].get('drive_size') is None:
 
             raise exception.ApiError(_("Invalid drive type %s")
                                         % vol_type['name'])
@@ -162,7 +162,7 @@ class API(base.Base):
         if storage is None:
             storage = []
 
-        if shared is None or shared == 'False' or shared == False:
+        if not shared or shared == 'False':
             shared = False
         else:
             shared = True