dynamic_traits.py

In [2]: from enthought.traits.api import HasTraits, Int

In [3]: from cPickle import dumps, loads

In [9]: a = HasTraits()

In [10]: a.add_trait('foo', Int)

In [11]: a.foo = 1

In [12]: a.foo = 'a'
---------------------------------------------------------------------------
TraitError                                Traceback (most recent call last)

TraitError: The 'foo' trait of a HasTraits instance must be an integer, but a value of 'a' <type 'str'> was specified.

In [13]: pkld_a = dumps(a)

In [14]: unpkld_a = loads(pkld_a)

In [16]: unpkld_a.foo
Out[16]: 1

In [17]: unpkld_a.foo = 'a'

In [18]: unpkld_a.foo
Out[18]: 'a'

test_dynamic_traits.py

def test_dynamic_traits():
    from nose.tools import assert_raises
    from traits.api import HasTraits, Int
    from cPickle import dumps, loads
    a = HasTraits()
    a.add_trait('foo', Int)
    a.foo = 1
    assign_a = lambda : setattr(a, 'foo', 'a')
    assert_raises(Exception, assign_a)
    pkld_a = dumps(a)
    unpkld_a = loads(pkld_a)
    assign_a_again = lambda : setattr(unpkld_a, 'foo', 'a')    
    assert_raises(Exception, assign_a_again)