GroupEditor does not call super()

[corranwebster]

The helper class GroupEditor does not call super() in its __init__() and so Traits will not properly initialize:

traitsui/traitsui/qt4/ui_panel.py

Lines 1255 to 1262 in 7681a2b

	class GroupEditor(Editor):
	""" A pseudo-editor that allows a group to be managed.
	"""
	def __init__(self, **traits):
	""" Initialise the object.
	"""
	self.trait_set(**traits)

(similarly for wx).

This could be part of the problem for issues involving enabled_when, etc not applying to labels or other components (eg. #758) or updating properly (or not, but it definitely and anti-pattern for Traits to do this).

[aaronayres35]

This is a bit awkward because super would end up calling:

traitsui/traitsui/editor.py

Lines 523 to 538 in 0c30b77

	def __init__(self, parent, **traits):
	""" Initializes the editor object.
	"""
	super().__init__(**traits)
	try:
	self.old_value = getattr(self.object, self.name)
	except AttributeError:
	ctrait = self.object.base_trait(self.name)
	if ctrait.type == "event" or self.name == "spring":
	# Getting the attribute will fail for 'Event' traits:
	self.old_value = Undefined
	else:
	raise
	# Synchronize the application invalid state status with the editor's:
	self.sync_value(self.factory.invalid, "invalid", "from")

In this case, users of GroupEditor and its subclasses do not currently specify a parent. Further, looking at the body of the above method, the GroupEditor does not have a name / there is no specific trait the editor is editing, which will lead to a break in this call as self.name will be <undefined>. Perhaps we could directly call __init__ on the base class higher up the chain (in this case HasPrivateTraits).
ie. at the start of the GroupEditor.__init__ method call HasPrivateTraits.__init__(self, **traits) or super(Editor, self).__init__(**traits) but I feel like that smells a bit.
Also, as a side note, I am unsure why parent is a required positional arg in the above code as it is unused in the body of the method?

[corranwebster]

Right - I think that what is needed is a superclass of Editor which both GroupEditor and Editor inherit from. I've been looking into it and I'm not quite sure which bits of Editor that GroupEditor is using, but I think it is at least the enable/disable and visibility stuff, but also possibly the control creation/deletion code. It doesn't need the code for synchronization of traits with the UI context.

As a more immediate work-around, it might make sense to have GroupEditor.__init__() do a direct HasTraits.__init__() call, which will at least make sure that the Traits machinery is all properly hooked up.