python: Resolve pep8 comparison errors.

Resolve pep8 errors:

  E711 comparison to None should be 'if cond is None:'

The reason comparing against None with "is None" is preferred over
"== None" is because a class can define its own equality operator and
produce bizarre unexpected behavior.  Using "is None" has a very
explicit meaning that can not be overridden.

  E721 do not compare types, use 'isinstance()'

This one is actually a mistake by the tool in most cases.
'from ovs.db import types' looks just like types from the Python stdlib.
In those cases, use the full ovs.db.types name.  Fix one case where it
actually was types from the stdlib.

Signed-off-by: Russell Bryant <russell@ovn.org>
Acked-by: Ben Pfaff <blp@ovn.org>

python/ovs/db/idl.py

@@ -179,7 +179,7 @@ class Idl(object):
             if (msg.type == ovs.jsonrpc.Message.T_NOTIFY
                 and msg.method == "update"
                 and len(msg.params) == 2
-                and msg.params[0] == None):
+                and msg.params[0] is None):
                 # Database contents changed.
                 self.__parse_update(msg.params[1])
             elif (msg.type == ovs.jsonrpc.Message.T_REPLY

python/ovs/db/parser.py

@@ -80,7 +80,7 @@ def is_identifier(s):
 
 
 def json_type_to_string(type_):
-    if type_ == None:
+    if type_ is None:
         return "null"
     elif type_ == bool:
         return "boolean"

python/ovs/db/schema.py

@@ -17,7 +17,7 @@ import sys
 
 from ovs.db import error
 import ovs.db.parser
-from ovs.db import types
+import ovs.db.types
 
 
 def _check_id(name, json):
@@ -101,7 +101,8 @@ class DbSchema(object):
         return DbSchema.from_json(self.to_json())
 
     def __follow_ref_table(self, column, base, base_name):
-        if not base or base.type != types.UuidType or not base.ref_table_name:
+        if (not base or base.type != ovs.db.types.UuidType
+                or not base.ref_table_name):
             return
 
         base.ref_table = self.tables.get(base.ref_table_name)
@@ -181,7 +182,7 @@ class TableSchema(object):
         indexes_json = parser.get_optional("indexes", [list], [])
         parser.finish()
 
-        if max_rows == None:
+        if max_rows is None:
             max_rows = sys.maxint
         elif max_rows <= 0:
             raise error.Error("maxRows must be at least 1", json)
@@ -257,7 +258,8 @@ class ColumnSchema(object):
         parser = ovs.db.parser.Parser(json, "schema for column %s" % name)
         mutable = parser.get_optional("mutable", [bool], True)
         ephemeral = parser.get_optional("ephemeral", [bool], False)
-        type_ = types.Type.from_json(parser.get("type", [dict, str, unicode]))
+        type_ = ovs.db.types.Type.from_json(parser.get("type",
+                                                       [dict, str, unicode]))
         parser.finish()
 
         return ColumnSchema(name, mutable, not ephemeral, type_)

python/ovs/json.py

@@ -579,7 +579,7 @@ class Parser(object):
         elif self.parse_state != Parser.__parse_end:
             self.__error("unexpected end of input")
 
-        if self.error == None:
+        if self.error is None:
             assert len(self.stack) == 1
             return self.stack.pop()
         else:

python/ovs/jsonrpc.py

@@ -490,7 +490,7 @@ class Session(object):
                 request.id = "echo"
                 self.rpc.send(request)
         else:
-            assert action == None
+            assert action is None
 
     def wait(self, poller):
         if self.rpc is not None: