Add a type.__init__() method that enforces the same signature as

type.__new__(), and then calls object.__init__(cls), just to be anal.

This allows us to restore the code in string.py's _TemplateMetaclass
that called super(...).__init__(name, bases, dct), which I commented
out yesterday since it broke due to the stricter argument checking
added to object.__init__().

Lib/string.py

@@ -108,9 +108,7 @@ class _TemplateMetaclass(type):
     """
 
     def __init__(cls, name, bases, dct):
-        # A super call makes no sense since type() doesn't define __init__().
-        # (Or does it? And should type.__init__() accept three args?)
-        # super(_TemplateMetaclass, cls).__init__(name, bases, dct)
+        super(_TemplateMetaclass, cls).__init__(name, bases, dct)
         if 'pattern' in dct:
             pattern = cls.pattern
         else:

Objects/typeobject.c

@@ -1684,6 +1684,39 @@ _unicode_to_string(PyObject *slots, Py_ssize_t nslots)
 }
 #endif
 
+/* Forward */
+static int
+object_init(PyObject *self, PyObject *args, PyObject *kwds);
+
+static int
+type_init(PyObject *cls, PyObject *args, PyObject *kwds)
+{
+	int res;
+
+	assert(args != NULL && PyTuple_Check(args));
+	assert(kwds == NULL || PyDict_Check(kwds));
+
+	if (kwds != NULL && PyDict_Check(kwds) && PyDict_Size(kwds) != 0) {
+		PyErr_SetString(PyExc_TypeError,
+				"type.__init__() takes no keyword arguments");
+		return -1;
+	}
+
+	if (args != NULL && PyTuple_Check(args) &&
+	    (PyTuple_GET_SIZE(args) != 1 && PyTuple_GET_SIZE(args) != 3)) {
+		PyErr_SetString(PyExc_TypeError,
+				"type.__init__() takes 1 or 3 arguments");
+		return -1;
+	}
+
+	/* Call object.__init__(self) now. */
+	/* XXX Could call super(type, cls).__init__() but what's the point? */
+	args = PyTuple_GetSlice(args, 0, 0);
+	res = object_init(cls, args, NULL);
+	Py_DECREF(args);
+	return res;
+}
+
 static PyObject *
 type_new(PyTypeObject *metatype, PyObject *args, PyObject *kwds)
 {
@@ -2381,7 +2414,7 @@ PyTypeObject PyType_Type = {
 	0,					/* tp_descr_get */
 	0,					/* tp_descr_set */
 	offsetof(PyTypeObject, tp_dict),	/* tp_dictoffset */
-	0,					/* tp_init */
+	type_init,				/* tp_init */
 	0,					/* tp_alloc */
 	type_new,				/* tp_new */
 	PyObject_GC_Del,			/* tp_free */