ErrorObserver.py

"""
This is a simple class that can catch errors from VTK objects.
"""

import vtk

class ErrorObserver:

   def __init__(self):
       self.__ErrorOccurred = False
       self.__ErrorMessage = None
       self.CallDataType = 'string0'

   def __call__(self, obj, event, message):
       self.__ErrorOccurred = True
       self.__ErrorMessage = message

   def ErrorOccurred(self):
       occ = self.__ErrorOccurred
       self.__ErrorOccurred = False
       return occ

   def ErrorMessage(self):
       return self.__ErrorMessage

e = ErrorObserver()

a = vtk.vtkImageReader()
a.AddObserver('ErrorEvent', e)

print "doing update"
a.Update()
if e.ErrorOccurred():
   print e.ErrorMessage()