Introducing __reduce_ex__, which is called with a protocol number argument
if it exists in preference over __reduce__. Now Tim can go implement this
in cPickle.c.
diff --git a/Lib/copy_reg.py b/Lib/copy_reg.py
index 6dc52c2..fa4ce72 100644
--- a/Lib/copy_reg.py
+++ b/Lib/copy_reg.py
@@ -109,6 +109,17 @@
dictitems = obj.iteritems()
return __newobj__, (cls,) + args, state, listitems, dictitems
+# Extended reduce:
+
+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:
+ return _reduce(obj)
+ else:
+ return _better_reduce(obj)
+
def _slotnames(cls):
"""Return a list of slot names for a given class.
diff --git a/Lib/pickle.py b/Lib/pickle.py
index c62bddc..f997f38 100644
--- a/Lib/pickle.py
+++ b/Lib/pickle.py
@@ -304,21 +304,20 @@
# Check copy_reg.dispatch_table
reduce = dispatch_table.get(t)
- if not reduce:
- # Check for a __reduce__ method.
- # Subtle: get the unbound method from the class, so that
- # protocol 2 can override the default __reduce__ that all
- # classes inherit from object. This has the added
- # advantage that the call always has the form reduce(obj)
- reduce = getattr(t, "__reduce__", None)
- if self.proto >= 2:
- # Protocol 2 can do better than the default __reduce__
- if reduce is object.__reduce__:
- reduce = _better_reduce
- if not reduce:
- raise PicklingError("Can't pickle %r object: %r" %
- (t.__name__, obj))
- rv = reduce(obj)
+ if reduce:
+ rv = reduce(obj)
+ else:
+ # Check for a __reduce_ex__ method, fall back to __reduce__
+ reduce = getattr(obj, "__reduce_ex__", None)
+ if reduce:
+ rv = reduce(self.proto)
+ else:
+ reduce = getattr(obj, "__reduce__", None)
+ if reduce:
+ rv = reduce()
+ else:
+ raise PicklingError("Can't pickle %r object: %r" %
+ (t.__name__, obj))
# Check for string returned by reduce(), meaning "save as global"
if type(rv) is StringType:
diff --git a/Lib/test/test_descrtut.py b/Lib/test/test_descrtut.py
index 66cb749..5fa0897 100644
--- a/Lib/test/test_descrtut.py
+++ b/Lib/test/test_descrtut.py
@@ -210,6 +210,7 @@
'__ne__',
'__new__',
'__reduce__',
+ '__reduce_ex__',
'__repr__',
'__rmul__',
'__setattr__',
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index e238056..a1e5b88 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -2441,11 +2441,15 @@
};
static PyObject *
-object_reduce(PyObject *self, PyObject *args)
+object_reduce_ex(PyObject *self, PyObject *args)
{
- /* Call copy_reg._reduce(self) */
+ /* Call copy_reg._reduce_ex(self, proto) */
static PyObject *copy_reg_str;
PyObject *copy_reg, *res;
+ int proto = 0;
+
+ if (!PyArg_ParseTuple(args, "|i:__reduce_ex__", &proto))
+ return NULL;
if (!copy_reg_str) {
copy_reg_str = PyString_InternFromString("copy_reg");
@@ -2455,13 +2459,15 @@
copy_reg = PyImport_Import(copy_reg_str);
if (!copy_reg)
return NULL;
- res = PyEval_CallMethod(copy_reg, "_reduce", "(O)", self);
+ res = PyEval_CallMethod(copy_reg, "_reduce_ex", "(Oi)", self, proto);
Py_DECREF(copy_reg);
return res;
}
static PyMethodDef object_methods[] = {
- {"__reduce__", object_reduce, METH_NOARGS,
+ {"__reduce_ex__", object_reduce_ex, METH_VARARGS,
+ PyDoc_STR("helper for pickle")},
+ {"__reduce__", object_reduce_ex, METH_VARARGS,
PyDoc_STR("helper for pickle")},
{0}
};