Improve NotImplementedError message.

src/jflow/workflow.py

@@ -466,11 +466,11 @@ class Workflow(threading.Thread):
         """ 
         Run the workflow, has to be implemented by subclasses
         """
-        raise NotImplementedError
+        raise NotImplementedError( "Workflow.process() must be implemented in " + self.__class__.__name__ )
 
     def get_name(self):
         """ 
-        Return the workflow name, has to be implemented by subclasses
+        Return the workflow name.
         """
         return self.__class__.__name__.lower()
     
@@ -478,13 +478,13 @@ class Workflow(threading.Thread):
         """ 
         Return the workflow description, has to be implemented by subclasses
         """
-        raise NotImplementedError
+        raise NotImplementedError( "Workflow.get_description() must be implemented in " + self.__class__.__name__ )
     
     def define_parameters(self, parameters_section=None):
         """ 
         Define the workflow parameters, has to be implemented by subclasses
         """
-        raise NotImplementedError
+        raise NotImplementedError( "Workflow.define_parameters() must be implemented in " + self.__class__.__name__ )
     
     def post_process(self):
         pass