1.3.0 cloudpickle.load hits AttributeError: module 'types' has no attribute 'ClassType'

[mzhang-code]

After upgrading to 1.3.0 from 1.2.2, our load() code starts having this issue.

 File "/usr/local/lib/python3.6/site-packages/cloudpickle/cloudpickle.py", line 415, in _builtin_type
     return getattr(types, name)
 AttributeError: module 'types' has no attribute 'ClassType'

Also found this post described the same issue we got. mlflow/mlflow#2429

I suspect it is caused by #337 "Fix a side effect that would redefine types.ClassTypes as type when importing cloudpickle", which removed types.ClassType = type

[ogrisel]

Coming back to this issue. As per cloudpickle's README and and as I replied in mlflow/mlflow#2429 (comment) , cloudpickle does not support loading objects from prior versions as it's only meant to transient object flowing between the nodes of a cluster.

That being said we could temporarily do an effort for backward compat this time with something like:

if not hasattr(types, "ClassType"):
    types.ClassType = type

but this is weird and I would rather not have this on the long term.

[pierreglaser]

That being said we could temporarily do an effort for backward compat this time with something like:

I'm afraid the proposed workaround will end up recreating the problem reported in #337.

[pierreglaser]

What might work though is special-casing type in

cloudpickle/cloudpickle/cloudpickle.py

Lines 390 to 391 in a69b92d

	def _builtin_type(name):
	return getattr(types, name)

[ogrisel]

Yes, this is what I was coming to by reading the reports. Let's add a small compat fix there.

[ogrisel]

Compat fix implemented in #359.