Make str and tuple types subclassable.

diff --git a/Objects/stringobject.c b/Objects/stringobject.c
index 13328812bbd2a56a1636c40c44c4d4937ddf7117..7675f7eb219419d5d588675429be4f372fa8d30b 100644 (file)
--- a/Objects/stringobject.c
+++ b/Objects/stringobject.c
@@ -2683,13 +2683,17 @@ string_methods[] = {
        {NULL,     NULL}                     /* sentinel */
 };
 
+staticforward PyObject *
+str_subtype_new(PyTypeObject *type, PyObject *args, PyObject *kwds);
+
 static PyObject *
 string_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
 {
        PyObject *x = NULL;
        static char *kwlist[] = {"object", 0};
 
-       assert(type == &PyString_Type);
+       if (type != &PyString_Type)
+               return str_subtype_new(type, args, kwds);
        if (!PyArg_ParseTupleAndKeywords(args, kwds, "|O:str", kwlist, &x))
                return NULL;
        if (x == NULL)
@@ -2697,6 +2701,24 @@ string_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
        return PyObject_Str(x);
 }
 
+static PyObject *
+str_subtype_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
+{
+       PyObject *tmp, *new;
+       int n;
+
+       assert(PyType_IsSubtype(type, &PyString_Type));
+       tmp = string_new(&PyString_Type, args, kwds);
+       if (tmp == NULL)
+               return NULL;
+       assert(PyString_Check(tmp));
+       new = type->tp_alloc(type, n = PyString_GET_SIZE(tmp));
+       if (new == NULL)
+               return NULL;
+       memcpy(PyString_AS_STRING(new), PyString_AS_STRING(tmp), n+1);
+       return new;
+}
+
 static char string_doc[] =
 "str(object) -> string\n\
 \n\
@@ -2724,7 +2746,7 @@ PyTypeObject PyString_Type = {
        PyObject_GenericGetAttr,                /* tp_getattro */
        0,                                      /* tp_setattro */
        &string_as_buffer,                      /* tp_as_buffer */
-       Py_TPFLAGS_DEFAULT,                     /* tp_flags */
+       Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /* tp_flags */
        string_doc,                             /* tp_doc */
        0,                                      /* tp_traverse */
        0,                                      /* tp_clear */

diff --git a/Objects/tupleobject.c b/Objects/tupleobject.c
index 5d01a9923d1de683386db395872373f67b2ab366..9ae732f567e35da83be5f5b7ff84019e5a37a6e5 100644 (file)
--- a/Objects/tupleobject.c
+++ b/Objects/tupleobject.c
@@ -475,13 +475,17 @@ tuplerichcompare(PyObject *v, PyObject *w, int op)
        return PyObject_RichCompare(vt->ob_item[i], wt->ob_item[i], op);
 }
 
+staticforward PyObject *
+tuple_subtype_new(PyTypeObject *type, PyObject *args, PyObject *kwds);
+
 static PyObject *
 tuple_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
 {
        PyObject *arg = NULL;
        static char *kwlist[] = {"sequence", 0};
 
-       assert(type == &PyTuple_Type);
+       if (type != &PyTuple_Type)
+               return tuple_subtype_new(type, args, kwds);
        if (!PyArg_ParseTupleAndKeywords(args, kwds, "|O:tuple", kwlist, &arg))
                return NULL;
 
@@ -491,6 +495,29 @@ tuple_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
                return PySequence_Tuple(arg);
 }
 
+static PyObject *
+tuple_subtype_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
+{
+       PyObject *tmp, *new, *item;
+       int i, n;
+
+       assert(PyType_IsSubtype(type, &PyTuple_Type));
+       tmp = tuple_new(&PyTuple_Type, args, kwds);
+       if (tmp == NULL)
+               return NULL;
+       assert(PyTuple_Check(tmp));
+       new = type->tp_alloc(type, n = PyTuple_GET_SIZE(tmp));
+       if (new == NULL)
+               return NULL;
+       for (i = 0; i < n; i++) {
+               item = PyTuple_GET_ITEM(tmp, i);
+               Py_INCREF(item);
+               PyTuple_SET_ITEM(new, i, item);
+       }
+       Py_DECREF(tmp);
+       return new;
+}
+
 static char tuple_doc[] =
 "tuple(sequence) -> list\n\
 \n\
@@ -529,7 +556,8 @@ PyTypeObject PyTuple_Type = {
        PyObject_GenericGetAttr,                /* tp_getattro */
        0,                                      /* tp_setattro */
        0,                                      /* tp_as_buffer */
-       Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,/* tp_flags */
+       Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
+               Py_TPFLAGS_BASETYPE,            /* tp_flags */
        tuple_doc,                              /* tp_doc */
        (traverseproc)tupletraverse,            /* tp_traverse */
        0,                                      /* tp_clear */