gistfile1.pyw

from enthought.traits.has_traits import HasTraits
from enthought.traits.trait_base import Undefined
from copy import deepcopy
from nipype.interfaces.traits import File

a = HasTraits()

a.add_trait('foo', File(exists=True))

a.foo = Undefined

print a.traits()

print a.traits()['foo'].trait_type

b = deepcopy(a)

print b.traits()

print b.traits()['foo'].trait_type

b.foo = 'idonotexist'

a.foo = 'idonotexist'