Added separate exception for trajectory precondition violations.

Author: psigen

src/prpy/base/robot.py

@@ -205,8 +205,8 @@ def PostProcessPath(self, path, defer=False, executor=None,
            curve through the waypoints (not implemented). If this curve is
            not collision free, then we fall back on...
         4. By default, we run a smoother that jointly times and smooths the
-           path via self.smoother. This algorithm can change the geometric path to
-           optimize runtime.
+           path via self.smoother. This algorithm can change the geometric path
+           to optimize runtime.
 
         The behavior in (2) and (3) can be forced by passing constrained=True
         or smooth=True. By default, the case is inferred by the tag(s) attached
@@ -411,8 +411,8 @@ def do_execute():
         else:
             raise ValueError('Received unexpected value "{:s}" for defer.'.format(str(defer)))
 
-
-    def ExecuteTrajectory(self, traj, defer=False, timeout=None, period=0.01, **kwargs):
+    def ExecuteTrajectory(self, traj, defer=False, timeout=None, period=0.01,
+                          **kwargs):
         """ Executes a time trajectory on the robot.
 
         This function directly executes a timed OpenRAVE trajectory on the
@@ -450,7 +450,7 @@ def ExecuteTrajectory(self, traj, defer=False, timeout=None, period=0.01, **kwar
         # Check that the current configuration of the robot matches the
         # initial configuration specified by the trajectory.
         if not util.IsAtTrajectoryStart(self, traj):
-            raise exceptions.TrajectoryAborted(
+            raise exceptions.TrajectoryNotExecutable(
                 'Trajectory started from different configuration than robot.')
 
         # If there was only one waypoint, at this point we are done!

src/prpy/exceptions.py

@@ -3,26 +3,44 @@ class PrPyException(Exception):
     Generic PrPy exception.
     """
 
+
+class TrajectoryNotExecutable(PrPyException):
+    """
+    Trajectory could not begin execution.
+
+    This exception typically indicates that some precondition of trajectory
+    execution was violated, such as the robot starting at a different
+    configuration, the trajectory not being in the correct format.
+
+    This exception indicates that the trajectory was not even attempted due to
+    one of these conditions.
+    """
+
+
 class TrajectoryAborted(PrPyException):
     """
     Trajectory was aborted.
     """
 
+
 class TrajectoryStalled(PrPyException):
     """
     Trajectory stalled.
     """
 
+
 class SynchronizationException(PrPyException):
     """
     Controller synchronization failed.
     """
 
+
 class SerializationException(PrPyException):
     """
     Serialization failed.
     """
 
+
 class UnsupportedTypeSerializationException(SerializationException):
     """
     Serialization failed due to an unknown type.
@@ -35,6 +53,7 @@ def __init__(self, value):
             'Serializing type "{:s}.{:s}" is not supported.'.format(
                 self.type.__module__, self.type.__name__))
 
+
 class UnsupportedTypeDeserializationException(SerializationException):
     """
     Deserialization failed due to an unknown type.