Patch #1462313, bug #1443328: the pickle modules now can handle classes

that have __private names in their __slots__.

Lib/copy_reg.py

@@ -116,8 +116,19 @@ def _slotnames(cls):
         # Slots found -- gather slot names from all base classes
         for c in cls.__mro__:
             if "__slots__" in c.__dict__:
-                names += [name for name in c.__dict__["__slots__"]
+                slots = c.__dict__['__slots__']
-                               if name not in ("__dict__", "__weakref__")]
+                # if class has a single slot, it can be given as a string
+                if isinstance(slots, basestring):
+                    slots = (slots,)
+                for name in slots:
+                    # special descriptors
+                    if name in ("__dict__", "__weakref__"):
+                        continue
+                    # mangled names
+                    elif name.startswith('__') and not name.endswith('__'):
+                        names.append('_%s%s' % (c.__name__, name))
+                    else:
+                        names.append(name)
 
     # Cache the outcome in the class if at all possible
     try:

Lib/test/test_copy_reg.py

@@ -8,6 +8,22 @@ class C:
     pass
 
 
+class WithoutSlots(object):
+    pass
+
+class WithWeakref(object):
+    __slots__ = ('__weakref__',)
+
+class WithPrivate(object):
+    __slots__ = ('__spam',)
+
+class WithSingleString(object):
+    __slots__ = 'spam'
+
+class WithInherited(WithSingleString):
+    __slots__ = ('eggs',)
+
+
 class CopyRegTestCase(unittest.TestCase):
 
     def test_class(self):
@@ -84,6 +100,19 @@ class CopyRegTestCase(unittest.TestCase):
             self.assertRaises(ValueError, copy_reg.add_extension,
                               mod, func, code)
 
+    def test_slotnames(self):
+        self.assertEquals(copy_reg._slotnames(WithoutSlots), [])
+        self.assertEquals(copy_reg._slotnames(WithWeakref), [])
+        expected = ['_WithPrivate__spam']
+        self.assertEquals(copy_reg._slotnames(WithPrivate), expected)
+        self.assertEquals(copy_reg._slotnames(WithSingleString), ['spam'])
+        expected = ['eggs', 'spam']
+        expected.sort()
+        result = copy_reg._slotnames(WithInherited)
+        result.sort()
+        self.assertEquals(result, expected)
+
+
 def test_main():
     test_support.run_unittest(CopyRegTestCase)
 

Misc/NEWS

@@ -487,6 +487,9 @@ Extension Modules
 Library
 -------
 
+- Patch #1462313, bug #1443328: the pickle modules now can handle classes
+  that have __private names in their __slots__.
+
 - Bug #1250170: mimetools now gracefully handles socket.gethostname()
   failures gracefully.