- A new type object, 'string', is added. This is a common base type

  for 'str' and 'unicode', and can be used instead of
  types.StringTypes, e.g. to test whether something is "a string":
  isinstance(x, string) is True for Unicode and 8-bit strings.  This
  is an abstract base class and cannot be instantiated directly.

diff --git a/Include/stringobject.h b/Include/stringobject.h
index 904945527e9a250346ef7c849eec8b2f9072104f..2a56ef639bf08b4b056d2bb65372d316225cd55c 100644 (file)
--- a/Include/stringobject.h
+++ b/Include/stringobject.h
@@ -39,6 +39,7 @@ typedef struct {
     char ob_sval[1];
 } PyStringObject;
 
+extern DL_IMPORT(PyTypeObject) PyBaseString_Type;
 extern DL_IMPORT(PyTypeObject) PyString_Type;
 
 #define PyString_Check(op) PyObject_TypeCheck(op, &PyString_Type)

diff --git a/Misc/NEWS b/Misc/NEWS
index ff3fdc6b752b0609755236b2b12eb5c03c325bcc..f544af42cf21cec0664739a2cb3c07512e85823d 100644 (file)
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -6,6 +6,12 @@ Type/class unification and new-style classes
 
 Core and builtins
 
+- A new type object, 'string', is added.  This is a common base type
+  for 'str' and 'unicode', and can be used instead of
+  types.StringTypes, e.g. to test whether something is "a string":
+  isinstance(x, string) is True for Unicode and 8-bit strings.  This
+  is an abstract base class and cannot be instantiated directly.
+
 - Deprecated features of xrange objects have been removed as
   promised.  The start, stop, and step attributes and the tolist()
   method no longer exist.  xrange repetition and slicing have been

diff --git a/Objects/object.c b/Objects/object.c
index 1bd8db924d8dd9ba27f7dc5791640ad26598f25d..b1bf2c3cdbdf1b8b3601986849a37f5a2a44bcb5 100644 (file)
--- a/Objects/object.c
+++ b/Objects/object.c
@@ -1779,6 +1779,9 @@ _Py_ReadyTypes(void)
        if (PyType_Ready(&PyBool_Type) < 0)
                Py_FatalError("Can't initialize 'bool'");
 
+       if (PyType_Ready(&PyString_Type) < 0)
+               Py_FatalError("Can't initialize 'str'");
+
        if (PyType_Ready(&PyList_Type) < 0)
                Py_FatalError("Can't initialize 'list'");
 

diff --git a/Objects/stringobject.c b/Objects/stringobject.c
index 668668ca4d0920813e8fdcb528937bb15735f9a3..27b3af4de1cd5b1d1739e143ed3fd3931a1742c3 100644 (file)
--- a/Objects/stringobject.c
+++ b/Objects/stringobject.c
@@ -2855,6 +2855,60 @@ str_subtype_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
        return pnew;
 }
 
+static PyObject *
+basestring_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
+{
+       PyErr_SetString(PyExc_TypeError,
+                       "The string type cannot be instantiated");
+       return NULL;
+}
+
+static char basestring_doc[] =
+"Type string cannot be instantiated; it is the base for str and unicode.";
+
+PyTypeObject PyBaseString_Type = {
+       PyObject_HEAD_INIT(&PyType_Type)
+       0,
+       "string",
+       0,
+       0,
+       0,                                      /* tp_dealloc */
+       0,                                      /* tp_print */
+       0,                                      /* tp_getattr */
+       0,                                      /* tp_setattr */
+       0,                                      /* tp_compare */
+       0,                                      /* tp_repr */
+       0,                                      /* tp_as_number */
+       0,                                      /* tp_as_sequence */
+       0,                                      /* tp_as_mapping */
+       0,                                      /* tp_hash */
+       0,                                      /* tp_call */
+       0,                                      /* tp_str */
+       0,                                      /* tp_getattro */
+       0,                                      /* tp_setattro */
+       0,                                      /* tp_as_buffer */
+       Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /* tp_flags */
+       basestring_doc,                         /* tp_doc */
+       0,                                      /* tp_traverse */
+       0,                                      /* tp_clear */
+       0,                                      /* tp_richcompare */
+       0,                                      /* tp_weaklistoffset */
+       0,                                      /* tp_iter */
+       0,                                      /* tp_iternext */
+       0,                                      /* tp_methods */
+       0,                                      /* tp_members */
+       0,                                      /* tp_getset */
+       &PyBaseObject_Type,                     /* tp_base */
+       0,                                      /* tp_dict */
+       0,                                      /* tp_descr_get */
+       0,                                      /* tp_descr_set */
+       0,                                      /* tp_dictoffset */
+       0,                                      /* tp_init */
+       0,                                      /* tp_alloc */
+       basestring_new,                         /* tp_new */
+       0,                                      /* tp_free */
+};
+
 static char string_doc[] =
 "str(object) -> string\n\
 \n\
@@ -2893,7 +2947,7 @@ PyTypeObject PyString_Type = {
        string_methods,                         /* tp_methods */
        0,                                      /* tp_members */
        0,                                      /* tp_getset */
-       0,                                      /* tp_base */
+       &PyBaseString_Type,                     /* tp_base */
        0,                                      /* tp_dict */
        0,                                      /* tp_descr_get */
        0,                                      /* tp_descr_set */

diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 5cc8455be6c2e50c20f4e919afc9c469ca7ad82f..0ac4941de160429d096021dfe78b9febbc9229a2 100644 (file)
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -5835,7 +5835,7 @@ PyTypeObject PyUnicode_Type = {
     unicode_methods,                   /* tp_methods */
     0,                                 /* tp_members */
     0,                                 /* tp_getset */
-    0,                                 /* tp_base */
+    &PyBaseString_Type,                        /* tp_base */
     0,                                 /* tp_dict */
     0,                                 /* tp_descr_get */
     0,                                 /* tp_descr_set */
@@ -5859,6 +5859,8 @@ void _PyUnicode_Init(void)
     strcpy(unicode_default_encoding, "ascii");
     for (i = 0; i < 256; i++)
        unicode_latin1[i] = NULL;
+    if (PyType_Ready(&PyUnicode_Type) < 0)
+       Py_FatalError("Can't initialize 'unicode'");
 }
 
 /* Finalize the Unicode implementation */

diff --git a/Python/bltinmodule.c b/Python/bltinmodule.c
index d0411e23ae74dcfe2803f80bd65a5b0f0e085b98..311176eb0db083358617f49903a3e70e48ac2430 100644 (file)
--- a/Python/bltinmodule.c
+++ b/Python/bltinmodule.c
@@ -1905,6 +1905,7 @@ _PyBuiltin_Init(void)
        SETBUILTIN("object",            &PyBaseObject_Type);
        SETBUILTIN("staticmethod",      &PyStaticMethod_Type);
        SETBUILTIN("str",               &PyString_Type);
+       SETBUILTIN("string",            &PyBaseString_Type);
        SETBUILTIN("super",             &PySuper_Type);
        SETBUILTIN("tuple",             &PyTuple_Type);
        SETBUILTIN("type",              &PyType_Type);