BUG: Fix bug pickling namedtuple.

Fixes a crash when trying to set `__dict__` onto a type when `__dict__`
is a property.

Author: Scott Sanderson

cloudpickle/cloudpickle.py

@@ -408,15 +408,18 @@ def save_dynamic_class(self, obj):
         from global modules.
         """
         clsdict = dict(obj.__dict__)  # copy dict proxy to a dict
-        if not isinstance(clsdict.get('__dict__', None), property):
-            # don't extract dict that are properties
-            clsdict.pop('__dict__', None)
-            clsdict.pop('__weakref__', None)
+        clsdict.pop('__weakref__', None)
 
-        # hack as __new__ is stored differently in the __dict__
-        new_override = clsdict.get('__new__', None)
-        if new_override:
-            clsdict['__new__'] = obj.__new__
+        # On PyPy, __doc__ is a readonly attribute, so we need to include it in
+        # the initial skeleton class.  This is safe because we know that the
+        # doc can't participate in a cycle with the original class.
+        type_kwargs = {'__doc__': clsdict.pop('__doc__', None)}
+
+        # If type overrides __dict__ as a property, include it in the type kwargs.
+        # In Python 2, we can't set this attribute after construction.
+        __dict__ = clsdict.pop('__dict__', None)
+        if isinstance(__dict__, property):
+            type_kwargs['__dict__'] = __dict__
 
         save = self.save
         write = self.write
@@ -439,17 +442,12 @@ def save_dynamic_class(self, obj):
         # Mark the start of the args for the rehydration function.
         write(pickle.MARK)
 
-        # On PyPy, __doc__ is a readonly attribute, so we need to include it in
-        # the initial skeleton class.  This is safe because we know that the
-        # doc can't participate in a cycle with the original class.
-        doc_dict = {'__doc__': clsdict.pop('__doc__', None)}
-
         # Create and memoize an empty class with obj's name and bases.
         save(type(obj))
         save((
             obj.__name__,
             obj.__bases__,
-            doc_dict,
+            type_kwargs,
         ))
         write(pickle.REDUCE)
         self.memoize(obj)

tests/cloudpickle_test.py

@@ -1,7 +1,7 @@
 from __future__ import division
 
 import abc
-
+import collections
 import base64
 import functools
 import imp
@@ -701,5 +701,14 @@ def test_function_module_name(self):
         func = lambda x: x
         self.assertEqual(pickle_depickle(func).__module__, func.__module__)
 
+    def test_namedtuple(self):
+        MyTuple = collections.namedtuple('MyTuple', ['a', 'b', 'c'])
+
+        t = MyTuple(1, 2, 3)
+        depickled_t = pickle_depickle(t)
+
+        self.assertEqual((depickled_t.a, depickled_t.b, depickled_t.c), (1, 2, 3))
+        self.assertEqual(vars(t), vars(depickled_t))
+
 if __name__ == '__main__':
     unittest.main()