Use a static and interned string for __subclasscheck__ and __instancecheck__ as suggested by Thomas Heller in #2115
diff --git a/Objects/abstract.c b/Objects/abstract.c
index 89a78c6..93d73bb 100644
--- a/Objects/abstract.c
+++ b/Objects/abstract.c
@@ -2401,10 +2401,17 @@
int
PyObject_IsInstance(PyObject *inst, PyObject *cls)
{
+ static PyObject *name = NULL;
PyObject *t, *v, *tb;
PyObject *checker;
PyErr_Fetch(&t, &v, &tb);
- checker = PyObject_GetAttrString(cls, "__instancecheck__");
+
+ if (name == NULL) {
+ name = PyString_InternFromString("__instancecheck__");
+ if (name == NULL)
+ return -1;
+ }
+ checker = PyObject_GetAttr(cls, name);
PyErr_Restore(t, v, tb);
if (checker != NULL) {
PyObject *res;
@@ -2477,10 +2484,17 @@
int
PyObject_IsSubclass(PyObject *derived, PyObject *cls)
{
+ static PyObject *name = NULL;
PyObject *t, *v, *tb;
PyObject *checker;
PyErr_Fetch(&t, &v, &tb);
- checker = PyObject_GetAttrString(cls, "__subclasscheck__");
+
+ if (name == NULL) {
+ name = PyString_InternFromString("__subclasscheck__");
+ if (name == NULL)
+ return -1;
+ }
+ checker = PyObject_GetAttr(cls, name);
PyErr_Restore(t, v, tb);
if (checker != NULL) {
PyObject *res;