forwardport of 2.3.5 fixes to copy.py

2 files changed, 120 insertions, 3 deletions

diff --git a/Lib/copy.py b/Lib/copy.py
index af905f3..45fc32d 100644
--- a/Lib/copy.py
+++ b/Lib/copy.py
@@ -62,6 +62,16 @@ except ImportError:
 
 __all__ = ["Error", "copy", "deepcopy"]
 
+import inspect
+def _getspecial(cls, name):
+    for basecls in inspect.getmro(cls):
+        try:
+            return basecls.__dict__[name]
+        except:
+            pass
+    else:
+        return None
+
 def copy(x):
     """Shallow copy operation on arbitrary Python objects.
 
@@ -74,7 +84,7 @@ def copy(x):
     if copier:
         return copier(x)
 
-    copier = getattr(cls, "__copy__", None)
+    copier = _getspecial(cls, "__copy__")
     if copier:
         return copier(x)
 
@@ -90,6 +100,9 @@ def copy(x):
             if reductor:
                 rv = reductor()
             else:
+                copier = getattr(x, "__copy__", None)
+                if copier:
+                    return copier()
                 raise Error("un(shallow)copyable object of type %s" % cls)
 
     return _reconstruct(x, rv, 0)
@@ -167,9 +180,9 @@ def deepcopy(x, memo=None, _nil=[]):
         if issc:
             y = _deepcopy_atomic(x, memo)
         else:
-            copier = getattr(x, "__deepcopy__", None)
+            copier = _getspecial(cls, "__deepcopy__")
             if copier:
-                y = copier(memo)
+                y = copier(x, memo)
             else:
                 reductor = dispatch_table.get(cls)
                 if reductor:
@@ -183,6 +196,9 @@ def deepcopy(x, memo=None, _nil=[]):
                         if reductor:
                             rv = reductor()
                         else:
+                            copier = getattr(x, "__deepcopy__", None)
+                            if copier:
+                                return copier(memo)
                             raise Error(
                                 "un(deep)copyable object of type %s" % cls)
                 y = _reconstruct(x, rv, 1, memo)
diff --git a/Lib/test/test_copy.py b/Lib/test/test_copy.py
index bd5a3e1..02dede4 100644
--- a/Lib/test/test_copy.py
+++ b/Lib/test/test_copy.py
@@ -166,6 +166,107 @@ class TestCopy(unittest.TestCase):
         x = C(42)
         self.assertEqual(copy.copy(x), x)
 
+    # tests for copying extension types, iff module trycopy is installed
+    def test_copy_classictype(self):
+        from _testcapi import make_copyable
+        x = make_copyable([23])
+        y = copy.copy(x)
+        self.assertEqual(x, y)
+        self.assertEqual(x.tag, y.tag)
+        self.assert_(x is not y)
+        self.assert_(x.tag is y.tag)
+
+    def test_deepcopy_classictype(self):
+        from _testcapi import make_copyable
+        x = make_copyable([23])
+        y = copy.deepcopy(x)
+        self.assertEqual(x, y)
+        self.assertEqual(x.tag, y.tag)
+        self.assert_(x is not y)
+        self.assert_(x.tag is not y.tag)
+
+    # regression tests for class-vs-instance and metaclass-confusion
+    def test_copy_classoverinstance(self):
+        class C(object):
+            def __init__(self, v):
+                self.v = v
+            def __cmp__(self, other):
+                return -cmp(other, self.v)
+            def __copy__(self):
+                return self.__class__(self.v)
+        x = C(23)
+        self.assertEqual(copy.copy(x), x)
+        x.__copy__ = lambda: 42
+        self.assertEqual(copy.copy(x), x)
+
+    def test_deepcopy_classoverinstance(self):
+        class C(object):
+            def __init__(self, v):
+                self.v = v
+            def __cmp__(self, other):
+                return -cmp(other, self.v)
+            def __deepcopy__(self, memo):
+                return self.__class__(copy.deepcopy(self.v, memo))
+        x = C(23)
+        self.assertEqual(copy.deepcopy(x), x)
+        x.__deepcopy__ = lambda memo: 42
+        self.assertEqual(copy.deepcopy(x), x)
+
+
+    def test_copy_metaclassconfusion(self):
+        class MyOwnError(copy.Error):
+            pass
+        class Meta(type):
+            def __copy__(cls):
+                raise MyOwnError("can't copy classes w/this metaclass")
+        class C:
+            __metaclass__ = Meta
+            def __init__(self, tag):
+                self.tag = tag
+            def __cmp__(self, other):
+                return -cmp(other, self.tag)
+        # the metaclass can forbid shallow copying of its classes
+        self.assertRaises(MyOwnError, copy.copy, C)
+        # check that there is no interference with instances
+        x = C(23)
+        self.assertEqual(copy.copy(x), x)
+
+    def test_deepcopy_metaclassconfusion(self):
+        class MyOwnError(copy.Error):
+            pass
+        class Meta(type):
+            def __deepcopy__(cls, memo):
+                raise MyOwnError("can't deepcopy classes w/this metaclass")
+        class C:
+            __metaclass__ = Meta
+            def __init__(self, tag):
+                self.tag = tag
+            def __cmp__(self, other):
+                return -cmp(other, self.tag)
+        # types are ALWAYS deepcopied atomically, no matter what
+        self.assertEqual(copy.deepcopy(C), C)
+        # check that there is no interference with instances
+        x = C(23)
+        self.assertEqual(copy.deepcopy(x), x)
+
+    def _nomro(self):
+        class C(type):
+            def __getattribute__(self, attr):
+                if attr == '__mro__':
+                    raise AttributeError, "What, *me*, a __mro__? Nevah!"
+                return super(C, self).__getattribute__(attr)
+        class D(object):
+            __metaclass__ = C
+        return D()
+
+    def test_copy_mro(self):
+        x = self._nomro()
+        y = copy.copy(x)
+
+    def test_deepcopy_mro(self):
+        x = self._nomro()
+        y = copy.deepcopy(x)
+
     # The deepcopy() method
 
     def test_deepcopy_basic(self):