[Python-checkins] cpython: Issue #20637: Key-sharing now also works for instance dictionaries of

Sun Feb 23 16:51:17 CET 2014

http://hg.python.org/cpython/rev/16229573e73e
changeset: 89335:16229573e73e
user: Antoine Pitrou <solipsis at pitrou.net>
date: Sun Feb 23 16:50:07 2014 +0100
summary:
 Issue #20637: Key-sharing now also works for instance dictionaries of subclasses. Patch by Peter Ingebretson.
files:
 Lib/test/test_types.py | 26 ++++++++++++++++++++++++--
 Misc/ACKS | 1 +
 Misc/NEWS | 6 ++++++
 Objects/typeobject.c | 3 +++
 4 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/Lib/test/test_types.py b/Lib/test/test_types.py
--- a/Lib/test/test_types.py
+++ b/Lib/test/test_types.py
@@ -1,6 +1,6 @@
 # Python test set -- part 6, built-in types
 
-from test.support import run_unittest, run_with_locale
+from test.support import run_unittest, run_with_locale, cpython_only
 import collections
 import pickle
 import locale
@@ -1170,9 +1170,31 @@
 self.assertEqual(ns, ns_roundtrip, pname)
 
 
+class SharedKeyTests(unittest.TestCase):
+
+ @cpython_only
+ def test_subclasses(self):
+ # Verify that subclasses can share keys (per PEP 412)
+ class A:
+ pass
+ class B(A):
+ pass
+
+ a, b = A(), B()
+ self.assertEqual(sys.getsizeof(vars(a)), sys.getsizeof(vars(b)))
+ self.assertLess(sys.getsizeof(vars(a)), sys.getsizeof({}))
+ a.x, a.y, a.z, a.w = range(4)
+ self.assertNotEqual(sys.getsizeof(vars(a)), sys.getsizeof(vars(b)))
+ a2 = A()
+ self.assertEqual(sys.getsizeof(vars(a)), sys.getsizeof(vars(a2)))
+ self.assertLess(sys.getsizeof(vars(a)), sys.getsizeof({}))
+ b.u, b.v, b.w, b.t = range(4)
+ self.assertLess(sys.getsizeof(vars(b)), sys.getsizeof({}))
+
+
 def test_main():
 run_unittest(TypesTests, MappingProxyTests, ClassCreationTests,
- SimpleNamespaceTests)
+ SimpleNamespaceTests, SharedKeyTests)
 
 if __name__ == '__main__':
 test_main()
diff --git a/Misc/ACKS b/Misc/ACKS
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -585,6 +585,7 @@
 Lars Immisch
 Bobby Impollonia
 Meador Inge
+Peter Ingebretson
 Tony Ingraldi
 John Interrante
 Bob Ippolito
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -5,6 +5,12 @@
 What's New in Python 3.4.1?
 ===========================
 
+Core and Builtins
+-----------------
+
+- Issue #20637: Key-sharing now also works for instance dictionaries of
+ subclasses. Patch by Peter Ingebretson.
+
 Library
 -------
 
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -2472,6 +2472,9 @@
 type->tp_dictoffset = slotoffset;
 slotoffset += sizeof(PyObject *);
 }
+ else if (!type->tp_dictoffset) {
+ type->tp_dictoffset = base->tp_dictoffset;
+ }
 if (type->tp_dictoffset) {
 et->ht_cached_keys = _PyDict_NewKeysForClass();
 }
-- 
Repository URL: http://hg.python.org/cpython
