Merge pull request #105 from GeckoRobotics/raise-more-specific-error-types

Remove usage of `raise Exception` in favor of more specific exception types

Author: gonzalocasas

AUTHORS.rst

@@ -8,3 +8,4 @@ Authors
 * Beverly Lytle `@beverlylytle <https://github.com/beverlylytle>`_
 * Alexis Jeandeau `@jeandeaual <https://github.com/jeandeaual>`_
 * Hiroyuki Obinata `@obi-t4 <https://github.com/obi-t4>`_
+* Domenic Rodriguez `@DomenicP <https://github.com/DomenicP>`_

CHANGELOG.rst

@@ -17,6 +17,7 @@ Unreleased
 * Switched to ``black`` for python code formatting.
 * Fix incompatible settings between ``black`` and ``flake8``.
 * Updated Github Actions workflows to remove python 3.6 builds.
+* Replaced occurrences of ``raise Exception`` with more specific ``Exception`` subclasses.
 
 **Fixed**
 

src/roslibpy/actionlib.py

@@ -136,7 +136,7 @@ def wait(self, timeout=None):
             Result of the goal.
         """
         if not self.wait_result.wait(timeout):
-            raise Exception("Goal failed to receive result")
+            raise TimeoutError("Goal failed to receive result")
 
         return self.result
 
@@ -226,7 +226,7 @@ def __init__(
         self.wait_status = threading.Event()
 
         if not self.wait_status.wait(DEFAULT_CONNECTION_TIMEOUT):
-            raise Exception("Action client failed to connect, no status received.")
+            raise TimeoutError("Action client failed to connect, no status received.")
 
     def _on_status_message(self, message):
         self.wait_status.set()

src/roslibpy/comm/comm_autobahn.py

@@ -232,7 +232,7 @@ def raise_timeout_exception(self, _result=None, _timeout=None):
         Raises:
             An exception.
         """
-        raise Exception("No service response received")
+        raise TimeoutError("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

@@ -126,12 +126,12 @@ def receive_chunk_async(self, task, context):
                 context['buffer']), self.factory.manager.cancellation_token)
             receive_task.ContinueWith.Overloads[Action[Task[WebSocketReceiveResult], object], object](
                 self.receive_chunk_async, context)
-        except Exception:
+        except Exception as exception:
             error_message = 'Exception on receive_chunk_async, processing will be aborted'
             if task:
                 error_message += '; Task status: {}, Inner exception: {}'.format(task.Status, task.Exception)
             LOGGER.exception(error_message)
-            raise
+            raise RosBridgeException(error_message) from exception
 
     def start_listening(self):
         """Starts listening asynchronously while the socket is open.
@@ -164,10 +164,10 @@ def start_listening(self):
                 except Exception:
                     LOGGER.exception('Exception on start_listening while trying to handle message received.' +
                                      'It could indicate a bug in user code on message handlers. Message skipped.')
-        except Exception:
-            LOGGER.exception(
-                'Exception on start_listening, processing will be aborted')
-            raise
+        except Exception as exception:
+            error_message = 'Exception on start_listening, processing will be aborted'
+            LOGGER.exception(error_message)
+            raise RosBridgeException(error_message) from exception
         finally:
             LOGGER.debug('Leaving the listening thread')
 
@@ -220,9 +220,10 @@ def send_chunk_async(self, task, message_data):
                 task.ContinueWith(lambda _res: self.semaphore.Release())
 
             return task
-        except Exception:
-            LOGGER.exception('Exception while on send_chunk_async')
-            raise
+        except Exception as exception:
+            error_message = 'Exception while on send_chunk_async'
+            LOGGER.exception(error_message)
+            raise RosBridgeException(error_message) from exception
 
     def send_message(self, payload):
         """Start sending a message over the websocket asynchronously."""
@@ -240,9 +241,10 @@ def send_message(self, payload):
                 None, [message_buffer, message_length, chunks_count, 0])
 
             return send_task
-        except Exception:
-            LOGGER.exception('Exception while sending message')
-            raise
+        except Exception as exception:
+            error_message = 'Exception while sending message'
+            LOGGER.exception(error_message)
+            raise RosBridgeException(error_message) from exception
 
     def dispose(self, *args):
         """Dispose the resources held by this protocol instance, i.e. socket."""
@@ -484,7 +486,7 @@ def raise_timeout_exception(self, _result=None, _timeout=None):
         Raises:
             An exception.
         """
-        raise Exception('No service response received')
+        raise TimeoutError('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

@@ -310,6 +310,12 @@ def unadvertise(self):
         self._advertise_id = None
 
 
+class ServiceException(Exception):
+    """Exception that is thrown when a service call fails."""
+
+    pass
+
+
 class Service(object):
     """Client/server of ROS services.
 
@@ -382,7 +388,7 @@ def call(self, request, callback=None, errback=None, timeout=None):
         # Blocking mode
         call_results = self.ros.call_sync_service(message, timeout)
         if "exception" in call_results:
-            raise Exception(call_results["exception"])
+            raise ServiceException(call_results["exception"])
 
         return call_results["result"]
 

src/roslibpy/ros.py

@@ -96,7 +96,7 @@ def run(self, timeout=CONNECTION_TIMEOUT):
         self.factory.on_ready(lambda _: wait_connect.set())
 
         if not wait_connect.wait(timeout):
-            raise Exception("Failed to connect to ROS")
+            raise TimeoutError("Failed to connect to ROS")
 
     def run_forever(self):
         """Kick-starts a blocking loop to wait for events.