From 7ea56b112e73081548e35ae27006e08e9189f896 Mon Sep 17 00:00:00 2001
From: Daniele Varrazzo <daniele.varrazzo@gmail.com>
Date: Sun, 8 Feb 2015 11:27:10 +0000
Subject: [PATCH] Make Column picklable on Python >= 3.3

Also expose the type from the extensions module, not from the main
module.
---
 lib/__init__.py         |  1 -
 lib/extensions.py       |  2 +-
 psycopg/psycopgmodule.c | 22 +++++++++++++++++++---
 3 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/lib/__init__.py b/lib/__init__.py
index a67c0930..cf8c06ae 100644
--- a/lib/__init__.py
+++ b/lib/__init__.py
@@ -55,7 +55,6 @@ from psycopg2._psycopg import DateFromTicks, TimeFromTicks, TimestampFromTicks
 from psycopg2._psycopg import Error, Warning, DataError, DatabaseError, ProgrammingError
 from psycopg2._psycopg import IntegrityError, InterfaceError, InternalError
 from psycopg2._psycopg import NotSupportedError, OperationalError
-from psycopg2._psycopg import Column
 
 from psycopg2._psycopg import _connect, apilevel, threadsafety, paramstyle
 from psycopg2._psycopg import __version__
diff --git a/lib/extensions.py b/lib/extensions.py
index 71a92b93..216d8ad2 100644
--- a/lib/extensions.py
+++ b/lib/extensions.py
@@ -58,7 +58,7 @@ except ImportError:
 
 from psycopg2._psycopg import adapt, adapters, encodings, connection, cursor, lobject, Xid
 from psycopg2._psycopg import string_types, binary_types, new_type, new_array_type, register_type
-from psycopg2._psycopg import ISQLQuote, Notify, Diagnostics
+from psycopg2._psycopg import ISQLQuote, Notify, Diagnostics, Column
 
 from psycopg2._psycopg import QueryCanceledError, TransactionRollbackError
 
diff --git a/psycopg/psycopgmodule.c b/psycopg/psycopgmodule.c
index 36f734c6..2c345a3b 100644
--- a/psycopg/psycopgmodule.c
+++ b/psycopg/psycopgmodule.c
@@ -621,8 +621,10 @@ psyco_GetDecimalType(void)
 static PyObject *
 psyco_make_description_type(void)
 {
-    PyObject *nt = NULL;
     PyObject *coll = NULL;
+    PyObject *nt = NULL;
+    PyTypeObject *t = NULL;
+    PyObject *s = NULL;
     PyObject *rv = NULL;
 
     /* Try to import collections.namedtuple */
@@ -636,12 +638,26 @@ psyco_make_description_type(void)
     }
 
     /* Build the namedtuple */
-    rv = PyObject_CallFunction(nt, "ss", "Column",
-        "name type_code display_size internal_size precision scale null_ok");
+    if(!(t = (PyTypeObject *)PyObject_CallFunction(nt, "ss", "Column",
+        "name type_code display_size internal_size precision scale null_ok"))) {
+        goto exit;
+    }
+
+    /* Export the tuple on the extensions module
+     * Required to guarantee picklability on Py > 3.3 (see Python issue 21374)
+     * for previous Py version the module is psycopg2 anyway but for consistency
+     * we'd rather expose it from the extensions module. */
+    if (!(s = Text_FromUTF8("psycopg2.extensions"))) { goto exit; }
+    if (0 > PyDict_SetItemString(t->tp_dict, "__module__", s)) { goto exit; }
+
+    rv = (PyObject *)t;
+    t = NULL;
 
 exit:
     Py_XDECREF(coll);
     Py_XDECREF(nt);
+    Py_XDECREF((PyObject *)t);
+    Py_XDECREF(s);
 
     return rv;