Give both wrapper classes a ``__getnewargs__`` method, which causes the ZODB...

Give both wrapper classes a ``__getnewargs__`` method, which causes the ZODB optimization to fail and create persistent references using the ``_p_oid`` alone. This happens to be the persistent oid of the wrapped object. This lets these objects to be persisted correctly, even though they are passed to the ZODB in a wrapped state.

CHANGES.txt

@@ -4,6 +4,12 @@ Changelog
 2.13.2 (unreleased)
 -------------------
 
+- Give both wrapper classes a ``__getnewargs__`` method, which causes the ZODB
+  optimization to fail and create persistent references using the ``_p_oid``
+  alone. This happens to be the persistent oid of the wrapped object. This lets
+  these objects to be persisted correctly, even though they are passed to the
+  ZODB in a wrapped state.
+
 - Added failing tests for http://dev.plone.org/plone/ticket/10318. This shows
   an edge-case where AQ wrappers can be pickled using the specific combination
   of cPickle, pickle protocol one and a custom Pickler class with an

src/Acquisition/_Acquisition.c

@@ -1290,6 +1290,12 @@ Wrappers_are_not_picklable(PyObject *wrapper, PyObject *args)
   return NULL;
 }
 
+static PyObject *
+Wrapper___getnewargs__(PyObject *self)
+{
+  return PyTuple_New(0);
+}
+
 static struct PyMethodDef Wrapper_methods[] = {
   {"acquire", (PyCFunction)Wrapper_acquire_method, 
    METH_VARARGS|METH_KEYWORDS,
@@ -1299,6 +1305,8 @@ static struct PyMethodDef Wrapper_methods[] = {
    "Get an attribute, acquiring it if necessary"},
   {"aq_inContextOf", (PyCFunction)Wrapper_inContextOf, METH_VARARGS,
    "Test whether the object is currently in the context of the argument"},
+  {"__getnewargs__", (PyCFunction)Wrapper___getnewargs__, METH_NOARGS,
+    "Get arguments to be passed to __new__"},
   {"__getstate__", (PyCFunction)Wrappers_are_not_picklable, METH_VARARGS,
    "Wrappers are not picklable"},
   {"__reduce__", (PyCFunction)Wrappers_are_not_picklable, METH_VARARGS,

src/Acquisition/tests.py

@@ -1570,6 +1570,7 @@ def test_cant_persist_acquisition_wrappers_classic():
     >>> import cPickle
 
     >>> class X:
+    ...     _p_oid = '1234'
     ...     def __getstate__(self):
     ...         return 1
 
@@ -1608,15 +1609,18 @@ def test_cant_persist_acquisition_wrappers_classic():
 
     >>> def persistent_id(obj):
     ...     klass = type(obj)
+    ...     oid = obj._p_oid
     ...     if hasattr(klass, '__getnewargs__'):
-    ...         return id(obj)
-    ...     return id(obj), klass
+    ...         return oid
+    ...     return 'class_and_oid', klass
 
     >>> pickler.inst_persistent_id = persistent_id
-    >>> pickler.dump(w)
-    Traceback (most recent call last):
-    ...
-    TypeError: Can't pickle objects in acquisition wrappers.
+    >>> _ = pickler.dump(w)
+    >>> state = file.getvalue()
+    >>> '1234' in state
+    True
+    >>> 'class_and_oid' in state
+    False
     """
 
 
@@ -1625,6 +1629,7 @@ def test_cant_persist_acquisition_wrappers_newstyle():
     >>> import cPickle
 
     >>> class X(object):
+    ...     _p_oid = '1234'
     ...     def __getstate__(self):
     ...         return 1
 
@@ -1663,15 +1668,18 @@ def test_cant_persist_acquisition_wrappers_newstyle():
 
     >>> def persistent_id(obj):
     ...     klass = type(obj)
+    ...     oid = obj._p_oid
     ...     if hasattr(klass, '__getnewargs__'):
-    ...         return id(obj)
-    ...     return id(obj), klass
+    ...         return oid
+    ...     return 'class_and_oid', klass
 
     >>> pickler.inst_persistent_id = persistent_id
-    >>> pickler.dump(w)
-    Traceback (most recent call last):
-    ...
-    TypeError: Can't pickle objects in acquisition wrappers.
+    >>> _ = pickler.dump(w)
+    >>> state = file.getvalue()
+    >>> '1234' in state
+    True
+    >>> 'class_and_oid' in state
+    False
     """