Pickle Serialization doesn't work for param.Parameterized with @param.depends function decorators about param

[samimia-swks]

What is interesting is that the current implementation of the depends() decorator, shown below, does use functools.wrap from the standard library; and that is supposed to solve the problem of pickeling decorated functions per this article...

@accept_arguments
def depends(func, *dependencies, watch=False, on_init=False, **kw):
    if iscoroutinefunction(func):
        @wraps(func)
        async def _depends(*args, **kw):
            return await func(*args, **kw)
    else:
        @wraps(func)
        def _depends(*args, **kw):
            return func(*args, **kw)

[maximlt]

Hi @steenha and @samimia-swks,

Param unfortunately doesn't have too many tests that exert serializing Param objects with pickle. I think it actually just has one!

param/tests/testparameterizedobject.py

Lines 383 to 388 in 154cdbe

	def test_pickle_instance(self):
	import pickle
	s = pickle.dumps(instance)
	instance.scale=0.8
	i = pickle.loads(s)
	self.assertEqual(i(),(0.3,18,[10,20,30]))

As it is it's not too surprising that pickling "more" complex objects fail :/ Contributions in this area are more than welcomed. It'd be for instance interesting to know whether pickling package_depends worked in the past, and if so what change (there were lots of changes in the internals of param.depends) broke it.