bpo-32492: 1.6x speed up in namedtuple attribute access using C fast-path (#10495)

* bpo-32492: 2.5x speed up in namedtuple attribute access using C fast path

* Add News entry

* fixup! bpo-32492: 2.5x speed up in namedtuple attribute access using C fast path

* Check for tuple in the __get__ of the new descriptor and don't cache the descriptor itself

* Don't inherit from property. Implement GC methods to handle __doc__

* Add a test for the docstring substitution in descriptors

* Update NEWS entry to reflect time against 3.7 branch

* Simplify implementation with argument clinic, better error messages, only __new__

* Use positional-only parameters for the __new__

* Use PyTuple_GET_SIZE and PyTuple_GET_ITEM to tighter the implementation of tuplegetterdescr_get

* Implement __set__ to make tuplegetter a data descriptor

* Use Py_INCREF now that we inline PyTuple_GetItem

* Apply the valid_index() function, saving one test

* Move Py_None test out of the critical path.

1 files changed, 28 insertions, 0 deletions

diff --git a/Modules/clinic/_collectionsmodule.c.h b/Modules/clinic/_collectionsmodule.c.h
new file mode 100644
index 0000000..12626c1
--- /dev/null
+++ b/Modules/clinic/_collectionsmodule.c.h
@@ -0,0 +1,28 @@
+/*[clinic input]
+preserve
+[clinic start generated code]*/
+
+static PyObject *
+tuplegetter_new_impl(PyTypeObject *type, Py_ssize_t index, PyObject *doc);
+
+static PyObject *
+tuplegetter_new(PyTypeObject *type, PyObject *args, PyObject *kwargs)
+{
+    PyObject *return_value = NULL;
+    Py_ssize_t index;
+    PyObject *doc;
+
+    if ((type == &tuplegetter_type) &&
+        !_PyArg_NoKeywords("_tuplegetter", kwargs)) {
+        goto exit;
+    }
+    if (!PyArg_ParseTuple(args, "nO:_tuplegetter",
+        &index, &doc)) {
+        goto exit;
+    }
+    return_value = tuplegetter_new_impl(type, index, doc);
+
+exit:
+    return return_value;
+}
+/*[clinic end generated code: output=83746071eacc28d3 input=a9049054013a1b77]*/