Pickling or copying dynamic traits makes them loose their type and metadata.

[chrisgorgo]

pickling

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

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

inp = pickle.dumps(a, -1)
b = pickle.loads(inp)


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

b.foo = 'idonotexist'
a.foo = 'idonotexist'

copying

In [68]: a = HasTraits()

In [69]: a.add_trait('foo', File(exists=True))

In [70]: a.foo = Undefined

In [71]: a.traits()['foo'].trait_type
Out[71]: <enthought.traits.trait_types.File object at 0x104809650>

In [72]: b = deepcopy(a)

In [73]: b.traits()['foo'].trait_type
Out[73]: <enthought.traits.trait_types.Python object at 0x10272b950>

In [74]: b.foo = 'idonotexist'

In [75]: a.foo = 'idonotexist'

[chrisgorgo]

It's still there in 4.0.1

[bpteague]

FWIW, I'm also getting bitten by this in v4.5.0.

[stefanoborini]

Verified also in 4.7.0

[mdickinson]

Regrettably, the fix for this in #373 had to be reverted in #462.

I'm leaving this issue closed, as it's mostly a duplicate of #16.