Fix pickling dataclasses

CHANGES.md

@@ -1,3 +1,10 @@
+0.8.0
+=====
+
+- Add support for pickling interactively defined dataclasses.
+  ([issue #245](https://github.com/cloudpipe/cloudpickle/pull/245))
+
+
 0.7.0
 =====
 

cloudpickle/cloudpickle.py

@@ -904,6 +904,12 @@ def save_root_logger(self, obj):
 
     dispatch[logging.RootLogger] = save_root_logger
 
+    if hasattr(types, "MappingProxyType"):
+        def _save_mappingproxy(self, obj):
+            self.save_reduce(types.MappingProxyType, (dict(obj),), obj=obj)
+
+        dispatch[types.MappingProxyType] = _save_mappingproxy
+
     """Special functions for Add-on libraries"""
     def inject_addons(self):
         """Plug in system. Register additional pickling functions if modules already loaded"""

tests/cloudpickle_test.py

@@ -1344,6 +1344,21 @@ def __init__(self):
                 with pytest.raises(AttributeError):
                     obj.non_registered_attribute = 1
 
+    @unittest.skipIf(not hasattr(types, "MappingProxyType"),
+                     "Old versions of Python do not have this type.")
+    def test_mappingproxy(self):
+        mp = types.MappingProxyType({"some_key": "some value"})
+        assert mp == pickle_depickle(mp, protocol=self.protocol)
+
+    def test_dataclass(self):
+        dataclasses = pytest.importorskip("dataclasses")
+
+        DataClass = dataclasses.make_dataclass('DataClass', [('x', int)])
+        data = DataClass(x=42)
+
+        pickle_depickle(DataClass, protocol=self.protocol)
+        assert data.x == pickle_depickle(data, protocol=self.protocol).x == 42
+
 
 class Protocol2CloudPickleTest(CloudPickleTest):