enthought/envisage — Issue #3: tasks example failure
Author: ddale
Created: 2011-11-10 18:29:13+00:00
State: open

I get the following when I try to run the tasks example from master, on OS X Lion (with qt4/PyQt4 and no wx):

```
[~/Projects/ets/envisage/examples/plugins/tasks/attractors](master)
darren@minerva $ python run.py
Exception occurred in traits notification handler.
Please check the log file for details.
Exception occurred in traits notification handler for object: , trait: active_model, old value: None, new value:
Traceback (most recent call last):
File "/Users/darren/Library/Python/2.7/lib/python/site-packages/traits-4.0.1-py2.7-macosx-10.7-x86_64.egg/traits/trait_notifiers.py", line 505, in rebind_call_0
self.dispatch( getattr( self.object(), self.name ) )
File "/Users/darren/Library/Python/2.7/lib/python/site-packages/traits-4.0.1-py2.7-macosx-10.7-x86_64.egg/traits/trait_notifiers.py", line 448, in dispatch
handler( *args )
File "/Users/darren/Projects/ets/envisage/examples/plugins/tasks/attractors/plot_3d_pane.py", line 49, in _update_scene
self.scene.mlab.clf()
File "/Users/darren/Library/Python/2.7/lib/python/site-packages/traits-4.0.1-py2.7-macosx-10.7-x86_64.egg/traits/trait_types.py", line 2776, in create_default_value
return klass( *args[1:], **kw )
File "/Users/darren/Library/Python/2.7/lib/python/site-packages/mayavi-4.0.1-py2.7-macosx-10.7-x86_64.egg/mayavi/tools/mlab_scene_model.py", line 41, in __init__
self.engine.current_scene = current_figure
File "/Users/darren/Library/Python/2.7/lib/python/site-packages/mayavi-4.0.1-py2.7-macosx-10.7-x86_64.egg/mayavi/core/engine.py", line 522, in _set_current_scene
self._current_scene = scene
File "/Users/darren/Library/Python/2.7/lib/python/site-packages/traits-4.0.1-py2.7-macosx-10.7-x86_64.egg/traits/trait_types.py", line 2690, in validate
self.validate_failed( object, name, value )
File "/Users/darren/Library/Python/2.7/lib/python/site-packages/traits-4.0.1-py2.7-macosx-10.7-x86_64.egg/traits/trait_types.py", line 2553, in validate_failed
self.error( object, name, value )
File "/Users/darren/Library/Python/2.7/lib/python/site-packages/traits-4.0.1-py2.7-macosx-10.7-x86_64.egg/traits/trait_handlers.py", line 168, in error
value )
TraitError: The '_current_scene' trait of an Engine instance must be an implementor of, or can be adapted to implement, Scene, but a value of None was specified.
ERROR:traits:Exception occurred in traits notification handler for object: , trait: active_model, old value: None, new value:
Traceback (most recent call last):
File "/Users/darren/Library/Python/2.7/lib/python/site-packages/traits-4.0.1-py2.7-macosx-10.7-x86_64.egg/traits/trait_notifiers.py", line 505, in rebind_call_0
self.dispatch( getattr( self.object(), self.name ) )
File "/Users/darren/Library/Python/2.7/lib/python/site-packages/traits-4.0.1-py2.7-macosx-10.7-x86_64.egg/traits/trait_notifiers.py", line 448, in dispatch
handler( *args )
File "/Users/darren/Projects/ets/envisage/examples/plugins/tasks/attractors/plot_3d_pane.py", line 49, in _update_scene
self.scene.mlab.clf()
File "/Users/darren/Library/Python/2.7/lib/python/site-packages/traits-4.0.1-py2.7-macosx-10.7-x86_64.egg/traits/trait_types.py", line 2776, in create_default_value
return klass( *args[1:], **kw )
File "/Users/darren/Library/Python/2.7/lib/python/site-packages/mayavi-4.0.1-py2.7-macosx-10.7-x86_64.egg/mayavi/tools/mlab_scene_model.py", line 41, in __init__
self.engine.current_scene = current_figure
File "/Users/darren/Library/Python/2.7/lib/python/site-packages/mayavi-4.0.1-py2.7-macosx-10.7-x86_64.egg/mayavi/core/engine.py", line 522, in _set_current_scene
self._current_scene = scene
File "/Users/darren/Library/Python/2.7/lib/python/site-packages/traits-4.0.1-py2.7-macosx-10.7-x86_64.egg/traits/trait_types.py", line 2690, in validate
self.validate_failed( object, name, value )
File "/Users/darren/Library/Python/2.7/lib/python/site-packages/traits-4.0.1-py2.7-macosx-10.7-x86_64.egg/traits/trait_types.py", line 2553, in validate_failed
self.error( object, name, value )
File "/Users/darren/Library/Python/2.7/lib/python/site-packages/traits-4.0.1-py2.7-macosx-10.7-x86_64.egg/traits/trait_handlers.py", line 168, in error
value )
TraitError: The '_current_scene' trait of an Engine instance must be an implementor of, or can be adapted to implement, Scene, but a value of None was specified.
```