Avoid shadowing Exception 'message' attribute

The Exception class has a 'message' attribute:

  >>> Exception('foo').message
  'foo'

however, we follow a pattern that results in the attribute being
shadowed by a class attribute:

  >>> class MyException(Exception):
  ...     message = 'Foo %s'
  ...     def __init__(self, bar):
  ...         message = self.message % bar
  ...         super(MyException, self).__init__(message)
  ...
  >>> MyException('bar').message
  'Foo %s'

whereas, we obviously want behaviour like this:

  >>> class MyException(Exception):
  ...     msg_fmt = 'Foo %s'
  ...     def __init__(self, bar):
  ...         message = self.msg_fmt % bar
  ...         super(MyException, self).__init__(message)
  ...
  >>> MyException('bar').message
  'Foo bar'

Avoid this shadowing by using 'msg_fmt' as the name of the class
attribute. Add a test which fails without this fix.

Change-Id: I304f31edec20b1293cf6c8de931415590fde6752

1 files changed, 10 insertions, 10 deletions

diff --git a/openstack/common/rpc/common.py b/openstack/common/rpc/common.py
index 5eacd32..9cfb942 100644
--- a/openstack/common/rpc/common.py
+++ b/openstack/common/rpc/common.py
@@ -74,14 +74,14 @@ _REMOTE_POSTFIX = '_Remote'
 
 
 class RPCException(Exception):
-    message = _("An unknown RPC related exception occurred.")
+    msg_fmt = _("An unknown RPC related exception occurred.")
 
     def __init__(self, message=None, **kwargs):
         self.kwargs = kwargs
 
         if not message:
             try:
-                message = self.message % kwargs
+                message = self.msg_fmt % kwargs
 
             except Exception:
                 # kwargs doesn't match a variable in the message
@@ -90,7 +90,7 @@ class RPCException(Exception):
                 for name, value in kwargs.iteritems():
                     LOG.error("%s: %s" % (name, value))
                 # at least get the core message out if something happened
-                message = self.message
+                message = self.msg_fmt
 
         super(RPCException, self).__init__(message)
 
@@ -104,7 +104,7 @@ class RemoteError(RPCException):
     contains all of the relevant info.
 
     """
-    message = _("Remote error: %(exc_type)s %(value)s\n%(traceback)s.")
+    msg_fmt = _("Remote error: %(exc_type)s %(value)s\n%(traceback)s.")
 
     def __init__(self, exc_type=None, value=None, traceback=None):
         self.exc_type = exc_type
@@ -121,7 +121,7 @@ class Timeout(RPCException):
     This exception is raised if the rpc_response_timeout is reached while
     waiting for a response from the remote side.
     """
-    message = _('Timeout while waiting on RPC response - '
+    msg_fmt = _('Timeout while waiting on RPC response - '
                 'topic: "%(topic)s", RPC method: "%(method)s" '
                 'info: "%(info)s"')
 
@@ -144,25 +144,25 @@ class Timeout(RPCException):
 
 
 class DuplicateMessageError(RPCException):
-    message = _("Found duplicate message(%(msg_id)s). Skipping it.")
+    msg_fmt = _("Found duplicate message(%(msg_id)s). Skipping it.")
 
 
 class InvalidRPCConnectionReuse(RPCException):
-    message = _("Invalid reuse of an RPC connection.")
+    msg_fmt = _("Invalid reuse of an RPC connection.")
 
 
 class UnsupportedRpcVersion(RPCException):
-    message = _("Specified RPC version, %(version)s, not supported by "
+    msg_fmt = _("Specified RPC version, %(version)s, not supported by "
                 "this endpoint.")
 
 
 class UnsupportedRpcEnvelopeVersion(RPCException):
-    message = _("Specified RPC envelope version, %(version)s, "
+    msg_fmt = _("Specified RPC envelope version, %(version)s, "
                 "not supported by this endpoint.")
 
 
 class RpcVersionCapError(RPCException):
-    message = _("Specified RPC version cap, %(version_cap)s, is too low")
+    msg_fmt = _("Specified RPC version cap, %(version_cap)s, is too low")
 
 
 class Connection(object):