Fix python 2.7 compatibility

Author: gonzalocasas

src/roslibpy/actionlib.py

@@ -29,6 +29,7 @@
 import time
 
 from . import Message, Topic
+from .core import RosTimeoutError
 from .event_emitter import EventEmitterMixin
 
 __all__ = ["Goal", "GoalStatus", "ActionClient", "SimpleActionServer"]
@@ -136,7 +137,7 @@ def wait(self, timeout=None):
             Result of the goal.
         """
         if not self.wait_result.wait(timeout):
-            raise TimeoutError("Goal failed to receive result")
+            raise RosTimeoutError("Goal failed to receive result")
 
         return self.result
 
@@ -226,7 +227,7 @@ def __init__(
         self.wait_status = threading.Event()
 
         if not self.wait_status.wait(DEFAULT_CONNECTION_TIMEOUT):
-            raise TimeoutError("Action client failed to connect, no status received.")
+            raise RosTimeoutError("Action client failed to connect, no status received.")
 
     def _on_status_message(self, message):
         self.wait_status.set()

src/roslibpy/comm/comm.py

@@ -11,7 +11,8 @@
 class RosBridgeException(Exception):
     """Exception raised on the ROS bridge communication."""
 
-    pass
+    def __init__(self, message, cause=None):
+        super(RosBridgeException, self).__init__(message, cause)
 
 
 class RosBridgeProtocol(object):

src/roslibpy/comm/comm_autobahn.py

@@ -13,6 +13,7 @@
 from twisted.internet.protocol import ReconnectingClientFactory
 from twisted.python import log
 
+from ..core import RosTimeoutError
 from ..event_emitter import EventEmitterMixin
 from . import RosBridgeProtocol
 
@@ -232,7 +233,7 @@ def raise_timeout_exception(self, _result=None, _timeout=None):
         Raises:
             An exception.
         """
-        raise TimeoutError("No service response received")
+        raise RosTimeoutError("No service response received")
 
     def get_inner_callback(self, result_placeholder):
         """Get the callback which, when called, provides result_placeholder with the result.

src/roslibpy/comm/comm_cli.py

@@ -24,6 +24,7 @@
 )
 from System.Threading.Tasks import Task
 
+from ..core import RosTimeoutError
 from ..event_emitter import EventEmitterMixin
 from . import RosBridgeException, RosBridgeProtocol
 
@@ -131,7 +132,7 @@ def receive_chunk_async(self, task, context):
             if task:
                 error_message += '; Task status: {}, Inner exception: {}'.format(task.Status, task.Exception)
             LOGGER.exception(error_message)
-            raise RosBridgeException(error_message) from exception
+            raise RosBridgeException(error_message, exception)
 
     def start_listening(self):
         """Starts listening asynchronously while the socket is open.
@@ -167,7 +168,7 @@ def start_listening(self):
         except Exception as exception:
             error_message = 'Exception on start_listening, processing will be aborted'
             LOGGER.exception(error_message)
-            raise RosBridgeException(error_message) from exception
+            raise RosBridgeException(error_message, exception)
         finally:
             LOGGER.debug('Leaving the listening thread')
 
@@ -223,7 +224,7 @@ def send_chunk_async(self, task, message_data):
         except Exception as exception:
             error_message = 'Exception while on send_chunk_async'
             LOGGER.exception(error_message)
-            raise RosBridgeException(error_message) from exception
+            raise RosBridgeException(error_message, exception)
 
     def send_message(self, payload):
         """Start sending a message over the websocket asynchronously."""
@@ -244,7 +245,7 @@ def send_message(self, payload):
         except Exception as exception:
             error_message = 'Exception while sending message'
             LOGGER.exception(error_message)
-            raise RosBridgeException(error_message) from exception
+            raise RosBridgeException(error_message, exception)
 
     def dispose(self, *args):
         """Dispose the resources held by this protocol instance, i.e. socket."""
@@ -486,7 +487,7 @@ def raise_timeout_exception(self, _result=None, _timeout=None):
         Raises:
             An exception.
         """
-        raise TimeoutError('No service response received')
+        raise RosTimeoutError('No service response received')
 
     def get_inner_callback(self, result_placeholder):
         """Get the callback which, when called, provides result_placeholder with the result.

src/roslibpy/core.py

@@ -12,7 +12,15 @@
 
 LOGGER = logging.getLogger("roslibpy")
 
-__all__ = ["Header", "Message", "Param", "Service", "ServiceRequest", "ServiceResponse", "Time", "Topic"]
+__all__ = ["Header", "Message", "Param", "RosTimeoutError", "Service", "ServiceRequest", "ServiceResponse", "Time", "Topic"]
+
+
+try:
+    class RosTimeoutError(TimeoutError):
+        pass
+except NameError:
+    class RosTimeoutError(Exception):
+        pass
 
 
 class Message(UserDict):

src/roslibpy/ros.py

@@ -5,6 +5,7 @@
 
 from . import Message, Param, Service, ServiceRequest, Time
 from .comm import RosBridgeClientFactory
+from .core import RosTimeoutError
 
 __all__ = ["Ros", "set_rosapi_timeout"]
 
@@ -96,7 +97,7 @@ def run(self, timeout=CONNECTION_TIMEOUT):
         self.factory.on_ready(lambda _: wait_connect.set())
 
         if not wait_connect.wait(timeout):
-            raise TimeoutError("Failed to connect to ROS")
+            raise RosTimeoutError("Failed to connect to ROS")
 
     def run_forever(self):
         """Kick-starts a blocking loop to wait for events.