Merged revisions 85154,85182 via svnmerge from

svn+ssh://pythondev@svn.python.org/python/branches/py3k

........
  r85154 | benjamin.peterson | 2010-10-01 19:03:31 -0500 (Fri, 01 Oct 2010) | 1 line

  type.__abstractmethods__ should raise an AttributeError #10006
........
  r85182 | benjamin.peterson | 2010-10-02 12:55:47 -0500 (Sat, 02 Oct 2010) | 1 line

  add a test and a note about metaclasses now being abcs
........

Lib/test/test_abc.py

@@ -60,6 +60,26 @@ class TestABC(unittest.TestCase):
             self.assertRaises(TypeError, F)  # because bar is abstract now
             self.assertTrue(isabstract(F))
 
+    def test_type_has_no_abstractmethods(self):
+        # type pretends not to have __abstractmethods__.
+        self.assertRaises(AttributeError, getattr, type, "__abstractmethods__")
+        class meta(type):
+            pass
+        self.assertRaises(AttributeError, getattr, meta, "__abstractmethods__")
+
+    def test_metaclass_abc(self):
+        # Metaclasses can be ABCs, too.
+        class A(metaclass=abc.ABCMeta):
+            @abc.abstractmethod
+            def x(self):
+                pass
+        self.assertEqual(A.__abstractmethods__, {"x"})
+        class meta(type, A):
+            def x(self):
+                return 1
+        class C(metaclass=meta):
+            pass
+
     def test_registration_basics(self):
         class A(metaclass=abc.ABCMeta):
             pass

Misc/NEWS

@@ -12,6 +12,9 @@ What's New in Python 3.1.3?
 Core and Builtins
 -----------------
 
+- Issue #10006: type.__abstractmethods__ now raises an AttributeError.  As a
+  result metaclasses can now be ABCs (see #9533).
+
 - Issue #9930: Remove bogus subtype check that was causing (e.g.)
   float.__rdiv__(2.0, 3) to return NotImplemented instead of the
   expected 1.5.

Objects/typeobject.c

@@ -320,8 +320,11 @@ type_set_module(PyTypeObject *type, PyObject *value, void *context)
 static PyObject *
 type_abstractmethods(PyTypeObject *type, void *context)
 {
-    PyObject *mod = PyDict_GetItemString(type->tp_dict,
-                                         "__abstractmethods__");
+    PyObject *mod = NULL;
+    /* type its self has an __abstractmethods__ descriptor (this). Don't
+       return that. */
+    if (type != &PyType_Type)
+        mod = PyDict_GetItemString(type->tp_dict, "__abstractmethods__");
     if (!mod) {
         PyErr_Format(PyExc_AttributeError, "__abstractmethods__");
         return NULL;