Make reversed() transparent with respect to length.
diff --git a/Lib/test/test_enumerate.py b/Lib/test/test_enumerate.py
index ab1a60d..00ecbcc 100644
--- a/Lib/test/test_enumerate.py
+++ b/Lib/test/test_enumerate.py
@@ -145,6 +145,10 @@
s = 'hello'
self.assertEqual(list(reversed(reversed(s))), list(s))
+ def test_len(self):
+ s = 'hello'
+ self.assertEqual(len(reversed(s)), len(s))
+
def test_main(verbose=None):
testclasses = (EnumerateTestCase, SubclassTestCase, TestEmpty, TestBig,
TestReversed)
diff --git a/Objects/enumobject.c b/Objects/enumobject.c
index 3aac680..55595ce 100644
--- a/Objects/enumobject.c
+++ b/Objects/enumobject.c
@@ -230,6 +230,12 @@
return item;
}
+static int
+reversed_len(reversedobject *ro)
+{
+ return PyObject_Size(ro->seq);
+}
+
static PyObject *
reversed_reverse(reversedobject *ro, PyObject *unused)
{
@@ -244,6 +250,12 @@
static PyMethodDef reversed_methods[] = {
{"__reversed__", (PyCFunction)reversed_reverse,
METH_NOARGS, reversed_doc},
+ {NULL, NULL} /* sentinel */
+};
+
+static PySequenceMethods reversed_as_sequence = {
+ (inquiry)reversed_len, /* sq_length */
+ 0, /* sq_concat */
};
PyTypeObject PyReversed_Type = {
@@ -260,7 +272,7 @@
0, /* tp_compare */
0, /* tp_repr */
0, /* tp_as_number */
- 0, /* tp_as_sequence */
+ &reversed_as_sequence, /* tp_as_sequence */
0, /* tp_as_mapping */
0, /* tp_hash */
0, /* tp_call */