Use __reduce_ex__ in copy.py. The test_*copy_cant() tests are simpler again.

Lib/copy.py

@@ -79,14 +79,20 @@ def copy(x):
         return copier(x)
 
     reductor = dispatch_table.get(cls)
-    if not reductor:
-        reductor = getattr(cls, "__reduce__", None)
-        if reductor == object.__reduce__:
-            reductor = _better_reduce
-        elif not reductor:
-            raise Error("un(shallow)copyable object of type %s" % cls)
-
-    return _reconstruct(x, reductor(x), 0)
+    if reductor:
+        rv = reductor(x)
+    else:
+        reductor = getattr(x, "__reduce_ex__", None)
+        if reductor:
+            rv = reductor(2)
+        else:
+            reductor = getattr(x, "__reduce__", None)
+            if reductor:
+                rv = reductor()
+            else:
+                raise Error("un(shallow)copyable object of type %s" % cls)
+
+    return _reconstruct(x, rv, 0)
     
 
 _copy_dispatch = d = {}
@@ -176,21 +182,27 @@ def deepcopy(x, memo=None, _nil=[]):
         except TypeError: # cls is not a class (old Boost; see SF #502085)
             issc = 0
         if issc:
-            copier = _deepcopy_atomic
+            y = _deepcopy_atomic(x, memo)
         else:
-            copier = getattr(cls, "__deepcopy__", None)
-
-        if copier:
-            y = copier(x, memo)
-        else:
-            reductor = dispatch_table.get(cls)
-            if not reductor:
-                reductor = getattr(cls, "__reduce__", None)
-                if reductor == object.__reduce__:
-                    reductor = _better_reduce
-                elif not reductor:
-                    raise Error("un(deep)copyable object of type %s" % cls)
-            y = _reconstruct(x, reductor(x), 1, memo)
+            copier = getattr(x, "__deepcopy__", None)
+            if copier:
+                y = copier(memo)
+            else:
+                reductor = dispatch_table.get(cls)
+                if reductor:
+                    rv = reductor(x)
+                else:
+                    reductor = getattr(x, "__reduce_ex__", None)
+                    if reductor:
+                        rv = reductor(2)
+                    else:
+                        reductor = getattr(x, "__reduce__", None)
+                        if reductor:
+                            rv = reductor()
+                        else:
+                            raise Error(
+                                "un(deep)copyable object of type %s" % cls)
+                y = _reconstruct(x, rv, 1, memo)
 
     memo[d] = y
     _keep_alive(x, memo) # Make sure x lives at least as long as d

Lib/copy_reg.py

@@ -113,9 +113,14 @@ def _better_reduce(obj):
 
 def _reduce_ex(obj, proto=0):
     obj_reduce = getattr(obj, "__reduce__", None)
-    if obj_reduce and obj.__class__.__reduce__ is not object.__reduce__:
-        return obj_reduce()
-    elif proto < 2:
+    # XXX This fails in test_copy.py line 61
+    if obj_reduce:
+        try:
+            if obj.__class__.__reduce__ is not object.__reduce__:
+                return obj_reduce()
+        except AttributeError:
+            pass
+    if proto < 2:
         return _reduce(obj)
     else:
         return _better_reduce(obj)

Lib/test/test_copy.py

@@ -46,6 +46,16 @@ class TestCopy(unittest.TestCase):
         copy_reg.pickle(C, pickle_C, C)
         y = copy.copy(x)
 
+    def test_copy_reduce_ex(self):
+        class C(object):
+            def __reduce_ex__(self, proto):
+                return ""
+            def __reduce__(self):
+                raise test_support.TestFailed, "shouldn't call this"
+        x = C()
+        y = copy.copy(x)
+        self.assert_(y is x)
+
     def test_copy_reduce(self):
         class C(object):
             def __reduce__(self):
@@ -55,13 +65,11 @@ class TestCopy(unittest.TestCase):
         self.assert_(y is x)
 
     def test_copy_cant(self):
-        class Meta(type):
+        class C(object):
             def __getattribute__(self, name):
-                if name == "__reduce__":
+                if name.startswith("__reduce"):
                     raise AttributeError, name
                 return object.__getattribute__(self, name)
-        class C:
-            __metaclass__ = Meta
         x = C()
         self.assertRaises(copy.Error, copy.copy, x)
 
@@ -209,6 +217,16 @@ class TestCopy(unittest.TestCase):
         copy_reg.pickle(C, pickle_C, C)
         y = copy.deepcopy(x)
 
+    def test_deepcopy_reduce_ex(self):
+        class C(object):
+            def __reduce_ex__(self, proto):
+                return ""
+            def __reduce__(self):
+                raise test_support.TestFailed, "shouldn't call this"
+        x = C()
+        y = copy.deepcopy(x)
+        self.assert_(y is x)
+
     def test_deepcopy_reduce(self):
         class C(object):
             def __reduce__(self):
@@ -218,13 +236,11 @@ class TestCopy(unittest.TestCase):
         self.assert_(y is x)
 
     def test_deepcopy_cant(self):
-        class Meta(type):
+        class C(object):
             def __getattribute__(self, name):
-                if name == "__reduce__":
+                if name.startswith("__reduce"):
                     raise AttributeError, name
                 return object.__getattribute__(self, name)
-        class C:
-            __metaclass__ = Meta
         x = C()
         self.assertRaises(copy.Error, copy.deepcopy, x)