diff -r 1f3242fb0c9c Modules/sha1module.c
--- a/Modules/sha1module.c	Thu Jan 09 19:03:32 2014 -0500
+++ b/Modules/sha1module.c	Fri Jan 10 12:00:37 2014 +0800
@@ -34,6 +34,17 @@
 #define SHA1_BLOCKSIZE    64
 #define SHA1_DIGESTSIZE   20
 
+/*[clinic input]
+module _sha1
+class _sha1.SHA1
+[clinic start generated code]*/
+/*[clinic end generated code: checksum=da39a3ee5e6b4b0d3255bfef95601890afd80709]*/
+/*[python input]
+class SHA1object_converter(self_converter):
+    type = "SHA1object *"
+[python start generated code]*/
+/*[python end generated code: checksum=da39a3ee5e6b4b0d3255bfef95601890afd80709]*/
+
 /* The structure for storing SHA1 info */
 
 struct sha1_state {
@@ -373,18 +384,28 @@
     return retval;
 }
 
-PyDoc_STRVAR(SHA1_update__doc__,
-"Update this hash object's state with the provided string.");
+/*[clinic input]
+_sha1.SHA1.update
+    self: SHA1object
+    obj: object
+    /
+
+Update this hash object's state with the provided string.
+[clinic start generated code]*/
+
+PyDoc_STRVAR(_sha1_SHA1_update__doc__,
+"update(obj)\n"
+"Update this hash object\'s state with the provided string.");
+
+#define _SHA1_SHA1_UPDATE_METHODDEF    \
+    {"update", (PyCFunction)_sha1_SHA1_update, METH_O, _sha1_SHA1_update__doc__},
 
 static PyObject *
-SHA1_update(SHA1object *self, PyObject *args)
+_sha1_SHA1_update(SHA1object *self, PyObject *obj)
+/*[clinic end generated code: checksum=e4215b9d33337c4a4f1f05705ab5ddcf3c65c599]*/
 {
-    PyObject *obj;
     Py_buffer buf;
 
-    if (!PyArg_ParseTuple(args, "O:update", &obj))
-        return NULL;
-
     GET_BUFFER_VIEW_OR_ERROUT(obj, &buf);
 
     sha1_process(&self->hash_state, buf.buf, buf.len);
@@ -398,7 +419,7 @@
     {"copy",      (PyCFunction)SHA1_copy,      METH_NOARGS,  SHA1_copy__doc__},
     {"digest",    (PyCFunction)SHA1_digest,    METH_NOARGS,  SHA1_digest__doc__},
     {"hexdigest", (PyCFunction)SHA1_hexdigest, METH_NOARGS,  SHA1_hexdigest__doc__},
-    {"update",    (PyCFunction)SHA1_update,    METH_VARARGS, SHA1_update__doc__},
+    _SHA1_SHA1_UPDATE_METHODDEF
     {NULL,        NULL}         /* sentinel */
 };
 
@@ -474,27 +495,53 @@
 
 /* The single module-level function: new() */
 
-PyDoc_STRVAR(SHA1_new__doc__,
+/*[clinic input]
+_sha1.SHA1.sha1
+
+    string: object = None
+
+Return a new SHA1 hash object; optionally initialized with a string.
+[clinic start generated code]*/
+
+PyDoc_STRVAR(_sha1_SHA1_sha1__doc__,
+"sha1(string=None)\n"
 "Return a new SHA1 hash object; optionally initialized with a string.");
 
+#define _SHA1_SHA1_SHA1_METHODDEF    \
+    {"sha1", (PyCFunction)_sha1_SHA1_sha1, METH_VARARGS|METH_KEYWORDS, _sha1_SHA1_sha1__doc__},
+
 static PyObject *
-SHA1_new(PyObject *self, PyObject *args, PyObject *kwdict)
+_sha1_SHA1_sha1_impl(PyObject *self, PyObject *string);
+
+static PyObject *
+_sha1_SHA1_sha1(PyObject *self, PyObject *args, PyObject *kwargs)
 {
-    static char *kwlist[] = {"string", NULL};
+    PyObject *return_value = NULL;
+    static char *_keywords[] = {"string", NULL};
+    PyObject *string = Py_None;
+
+    if (!PyArg_ParseTupleAndKeywords(args, kwargs,
+        "|O:sha1", _keywords,
+        &string))
+        goto exit;
+    return_value = _sha1_SHA1_sha1_impl(self, string);
+
+exit:
+    return return_value;
+}
+
+static PyObject *
+_sha1_SHA1_sha1_impl(PyObject *self, PyObject *string)
+/*[clinic end generated code: checksum=855cccc92a991cc651f3907f4b2293852856033c]*/
+{
     SHA1object *new;
-    PyObject *data_obj = NULL;
     Py_buffer buf;
 
-    if (!PyArg_ParseTupleAndKeywords(args, kwdict, "|O:new", kwlist,
-                                     &data_obj)) {
-        return NULL;
-    }
-
-    if (data_obj)
-        GET_BUFFER_VIEW_OR_ERROUT(data_obj, &buf);
+    if (string != Py_None)
+        GET_BUFFER_VIEW_OR_ERROUT(string, &buf);
 
     if ((new = newSHA1object()) == NULL) {
-        if (data_obj)
+        if (string != Py_None)
             PyBuffer_Release(&buf);
         return NULL;
     }
@@ -503,11 +550,11 @@
 
     if (PyErr_Occurred()) {
         Py_DECREF(new);
-        if (data_obj)
+        if (string != Py_None)
             PyBuffer_Release(&buf);
         return NULL;
     }
-    if (data_obj) {
+    if (string != Py_None) {
         sha1_process(&new->hash_state, buf.buf, buf.len);
         PyBuffer_Release(&buf);
     }
@@ -519,7 +566,7 @@
 /* List of functions exported by this module */
 
 static struct PyMethodDef SHA1_functions[] = {
-    {"sha1",(PyCFunction)SHA1_new, METH_VARARGS|METH_KEYWORDS,SHA1_new__doc__},
+    _SHA1_SHA1_SHA1_METHODDEF
     {NULL,      NULL}            /* Sentinel */
 };