#5228: add pickle support to functools.partial

diff --git a/Lib/test/test_functools.py b/Lib/test/test_functools.py
index 30d419da21d32db3acda8c81df8823454e30832f..cd645d34bf25a3a27dfc9634b08e48ba52133816 100644 (file)
--- a/Lib/test/test_functools.py
+++ b/Lib/test/test_functools.py
@@ -2,6 +2,7 @@ import functools
 import unittest
 from test import test_support
 from weakref import proxy
+import pickle
 
 @staticmethod
 def PythonPartial(func, *args, **keywords):
@@ -19,6 +20,10 @@ def capture(*args, **kw):
     """capture all positional and keyword arguments"""
     return args, kw
 
+def signature(part):
+    """ return the signature of a partial object """
+    return (part.func, part.args, part.keywords, part.__dict__)
+
 class TestPartial(unittest.TestCase):
 
     thetype = functools.partial
@@ -140,6 +145,12 @@ class TestPartial(unittest.TestCase):
         join = self.thetype(''.join)
         self.assertEqual(join(data), '0123456789')
 
+    def test_pickle(self):
+        f = self.thetype(signature, 'asdf', bar=True)
+        f.add_something_to__dict__ = True
+        f_copy = pickle.loads(pickle.dumps(f))
+        self.assertEqual(signature(f), signature(f_copy))
+
 class PartialSubclass(functools.partial):
     pass
 
@@ -147,11 +158,13 @@ class TestPartialSubclass(TestPartial):
 
     thetype = PartialSubclass
 
-
 class TestPythonPartial(TestPartial):
 
     thetype = PythonPartial
 
+    # the python version isn't picklable
+    def test_pickle(self): pass
+
 class TestUpdateWrapper(unittest.TestCase):
 
     def check_wrapper(self, wrapper, wrapped,

diff --git a/Misc/ACKS b/Misc/ACKS
index d5b055cd90283aa0d6c99104489e42fa042a8367..b7cd25a75b139586b9245e2cb99bdee6c2e3b834 100644 (file)
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -168,6 +168,7 @@ Roger Dev
 Raghuram Devarakonda
 Toby Dickenson
 Mark Dickinson
+Jack Diederich
 Yves Dionne
 Daniel Dittmar
 Jaromir Dolecek

diff --git a/Misc/NEWS b/Misc/NEWS
index 3d15073ef8e6bd3b50a417bdf2aa8c05e696c176..62b37f211a5663fd589281a3ac6f051b81e144a7 100644 (file)
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -710,6 +710,8 @@ Extension Modules
 
 - Issue #4396: The parser module now correctly validates the with statement.
 
+- Issue #5228: Make functools.partial objects can now be pickled.
+
 Tests
 -----
 

diff --git a/Modules/_functoolsmodule.c b/Modules/_functoolsmodule.c
index 5dfbc15c139eea1a7eb917ef86d7883a001b116b..92fa4cb955dbd0dae4311684812be9c65b965e9e 100644 (file)
--- a/Modules/_functoolsmodule.c
+++ b/Modules/_functoolsmodule.c
@@ -274,6 +274,53 @@ static PyGetSetDef partial_getsetlist[] = {
        {NULL} /* Sentinel */
 };
 
+/* Pickle strategy:
+   __reduce__ by itself doesn't support getting kwargs in the unpickle
+   operation so we define a __setstate__ that replaces all the information
+   about the partial.  If we only replaced part of it someone would use
+   it as a hook to do stange things.
+ */
+
+PyObject *
+partial_reduce(partialobject *pto, PyObject *unused)
+{
+       return Py_BuildValue("O(O)(OOOO)", Py_TYPE(pto), pto->fn, pto->fn, 
+                            pto->args, pto->kw,
+                            pto->dict ? pto->dict : Py_None);
+}
+
+PyObject *
+partial_setstate(partialobject *pto, PyObject *args)
+{
+       PyObject *fn, *fnargs, *kw, *dict;
+       if (!PyArg_ParseTuple(args, "(OOOO):__setstate__", 
+                             &fn, &fnargs, &kw, &dict))
+               return NULL;
+       Py_XDECREF(pto->fn);
+       Py_XDECREF(pto->args);
+       Py_XDECREF(pto->kw);
+       Py_XDECREF(pto->dict);
+       pto->fn = fn;
+       pto->args = fnargs;
+       pto->kw = kw;
+       if (dict != Py_None) {
+         pto->dict = dict;
+         Py_INCREF(dict);
+       } else {
+         pto->dict = NULL;
+       }
+       Py_INCREF(fn);
+       Py_INCREF(fnargs);
+       Py_INCREF(kw);
+       Py_RETURN_NONE;
+}
+
+static PyMethodDef partial_methods[] = {
+       {"__reduce__", (PyCFunction)partial_reduce, METH_NOARGS},
+       {"__setstate__", (PyCFunction)partial_setstate, METH_VARARGS},
+       {NULL,          NULL}           /* sentinel */
+};
+
 static PyTypeObject partial_type = {
        PyVarObject_HEAD_INIT(NULL, 0)
        "functools.partial",            /* tp_name */
@@ -304,7 +351,7 @@ static PyTypeObject partial_type = {
        offsetof(partialobject, weakreflist),   /* tp_weaklistoffset */
        0,                              /* tp_iter */
        0,                              /* tp_iternext */
-       0,                              /* tp_methods */
+       partial_methods,                /* tp_methods */
        partial_memberlist,             /* tp_members */
        partial_getsetlist,             /* tp_getset */
        0,                              /* tp_base */