- Fixed ``PyProxyBase.__iter__()`` to return the result of

  ``PyProxyBase._wrapped.__iter__`` if available, otherwise fall back to
  Python internals. The previous implementation always created a generator.

- Fixed ``PyProxyBase.__setattr__()`` to allow setting of properties on the
  proxy itself. This is needed to properly allow proxy extensions as was
  evidenced int he ``zope.security.decorator`` module.

CHANGES.rst

@@ -5,7 +5,13 @@ CHANGES
 4.1.2 (unreleased)
 ------------------
 
-- TBD
+- Fixed ``PyProxyBase.__iter__()`` to return the result of
+  ``PyProxyBase._wrapped.__iter__`` if available, otherwise fall back to
+  Python internals. The previous implementation always created a generator.
+
+- Fixed ``PyProxyBase.__setattr__()`` to allow setting of properties on the
+  proxy itself. This is needed to properly allow proxy extensions as was
+  evidenced int he ``zope.security.decorator`` module.
 
 4.1.1 (2012-12-31)
 ------------------
@@ -19,7 +25,7 @@ CHANGES
 
 - Replaced use of ``PyCObject`` APIs with equivalent ``PyCapsule`` APIs,
   except under Python 2.6.
-  
+
   N.B.  This change is an ABI incompatibility under Python 2.7:
         extensions built under Python 2.7 against 4.0.x versions of
         ``zope.proxy`` must be rebuilt.
@@ -37,7 +43,7 @@ CHANGES
   N.B.:  the C extension is *not* built under PyPy.
 
 - Added a pure-Python reference / fallback implementations of
-  ``zope.proxy.ProxyBase`` and the proxy module API functions.  
+  ``zope.proxy.ProxyBase`` and the proxy module API functions.
 
   N.B.:  the pure-Python proxy implements all regular features of
   ``ProxyBase``;  however, it does not exclude access to the wrapped object

src/zope/proxy/__init__.py

@@ -115,7 +115,12 @@ class PyProxyBase(object):
     def __setattr__(self, name, value):
         if name == '_wrapped':
             return super(PyProxyBase, self).__setattr__(name, value)
-        setattr(self._wrapped, name, value)
+        try:
+            mine = super(PyProxyBase, self).__getattribute__(name)
+        except AttributeError:
+            return setattr(self._wrapped, name, value)
+        else:
+            return object.__setattr__(self, name, value)
 
     def __delattr__(self, name):
         if name == '_wrapped':
@@ -150,8 +155,8 @@ class PyProxyBase(object):
         del self._wrapped[key]
 
     def __iter__(self):
-        for item in self._wrapped:
-            yield item
+        # This handles a custom __iter__ and generator support at the same time.
+        return iter(self._wrapped)
 
     def next(self):
         # Called when we wrap an iterator itself.

src/zope/proxy/tests/test_proxy.py

@@ -215,6 +215,20 @@ class PyProxyBaseTestCase(unittest.TestCase):
         w.foo = 1
         self.assertEqual(o.foo, 1)
 
+    def test___setattr__sets_proxy_property(self):
+        class Proxy(self._getTargetClass()):
+            bar = property(
+                lambda s: s.__dict__.get('_bar'),
+                lambda s, v: s.__dict__.__setitem__('_bar', v)
+                )
+        class Foo(object):
+            pass
+        o = Foo()
+        w = Proxy(o)
+        w.bar = 43
+        self.assertEqual(w.bar, 43)
+        self.assertRaises(AttributeError, getattr, o, 'bar')
+
     def test___delattr___wrapped(self):
         class Foo(object):
             pass
@@ -343,6 +357,19 @@ class PyProxyBaseTestCase(unittest.TestCase):
         t = tuple(self._makeOne(iter(a)))
         self.assertEqual(t, (1, 2, 3))
 
+    def test___iter___returns_self_if_defined(self):
+        # Return the wrapped object itself, if it is an iterator.
+        class MyIter(object):
+            def __iter__(self):
+                return self
+            def __next__(self):
+                return 42
+            next = __next__
+        myIter = MyIter()
+        p = self._makeOne(myIter)
+        self.assertEqual(iter(p), p)
+        self.assertTrue(isinstance(iter(p), MyIter))
+
     def test___iter___next_when_returned_by_iterable(self):
         # Wrap an iterator within the iteration protocol, expecting it
         # still to work.  PyObject_GetIter() will not be called on the