Change array.typecodes type to tuple

vstinner · May 4, 2026 · Apr 17, 2026 · Apr 17, 2026 · Apr 17, 2026 · Apr 17, 2026
commit cf16b041f5d9a27dbd02bd002ad38ecab563d376
diff --git a/Doc/library/array.rst b/Doc/library/array.rst
@@ -109,7 +109,10 @@ The module defines the following item:
 
 .. data:: typecodes
 
-   A string with all available type codes.
+   A tuple with all available type codes.
+
+   .. versionchanged:: next
+      The type changed from :str:`str` to :class:`tuple`.
 
 
 The module defines the following type:

@@ -680,12 +680,17 @@ array
 
 * Support the :c:expr:`float complex` and :c:expr:`double complex` C types:
   formatting characters ``'F'``/``'Zd'`` and ``'D'``/``'Zd'`` respectively.
-  (Contributed by Sergey B Kirpichev in :gh:`146151`.)
+  (Contributed by Sergey B Kirpichev and Victor Stinner in :gh:`146151`
+  and :gh:`148675`.)
 
 * Support half-floats (16-bit IEEE 754 binary interchange format): formatting
   character ``'e'``.
   (Contributed by Sergey B Kirpichev in :gh:`146238`.)
 
+* The :data:`array.typecodes` type changed from :str:`str` to :class:`tuple`
+  to support type codes longer than 1 character (``Zf`` and ``Zd``).
+  (Contributed by Victor Stinner in :gh:`148675`.)
+
 
 base64
 ------

diff --git a/Lib/test/test_array.py b/Lib/test/test_array.py
@@ -85,6 +85,12 @@ def __index__(self):
                 with self.assertRaises(TypeError):
                     a.fromlist(lst)
 
+    def test_typecodes(self):
+        self.assertIsInstance(array.typecodes, tuple)
+        for typecode in array.typecodes:
+            self.assertIsInstance(typecode, str)
+            self.assertGreaterEqual(len(typecode), 1)
+
 
 # Machine format codes.
 #
@@ -1237,6 +1243,9 @@ def test_free_after_iterating(self):
         support.check_free_after_iterating(self, reversed, array.array,
                                            (self.typecode,))
 
+    def test_known_typecode(self):
+        self.assertIn(self.typecode, array.typecodes)
+
 class StringTest(BaseTest):
 
     def test_setitem(self):

diff --git a/Misc/NEWS.d/next/Library/2026-05-02-12-30-35.gh-issue-148675.cu2YFT.rst b/Misc/NEWS.d/next/Library/2026-05-02-12-30-35.gh-issue-148675.cu2YFT.rst
@@ -0,0 +1,3 @@
+The :data:`array.typecodes` type changed from :str:`str` to :class:`tuple`
+to support type codes longer than 1 character (``Zf`` and ``Zd``). Patch by
+Victor Stinner.
diff --git a/Modules/arraymodule.c b/Modules/arraymodule.c
@@ -3493,7 +3493,6 @@ static int
 array_modexec(PyObject *m)
 {
     array_state *state = get_array_state(m);
-    char buffer[Py_ARRAY_LENGTH(descriptors)*2], *p;
     PyObject *typecodes;
     const struct arraydescr *descr;
 
@@ -3532,13 +3531,29 @@ array_modexec(PyObject *m)
         return -1;
     }
 
-    p = buffer;
+    typecodes = PyList_New(0);
+    if (typecodes == NULL) {
+        return -1;
+    }
     for (descr = descriptors; descr->typecode != NULL; descr++) {
-        strcpy(p, descr->typecode);
-        p += strlen(descr->typecode);
+        PyObject *typecode = PyUnicode_DecodeASCII(descr->typecode, strlen(descr->typecode), NULL);
+        if (typecode == NULL) {
+            Py_DECREF(typecodes);
+            return -1;
+        }
+        int res = PyList_Append(typecodes, typecode);
+        Py_DECREF(typecode);
+        if (res < 0) {
+            Py_DECREF(typecodes);
+            return -1;
+        }
+    }
+    PyObject *tuple = PyList_AsTuple(typecodes);
+    Py_DECREF(typecodes);
+    if (tuple == NULL) {
+        return -1;
     }
-    typecodes = PyUnicode_DecodeASCII(buffer, p - buffer, NULL);
-    if (PyModule_Add(m, "typecodes", typecodes) < 0) {
+    if (PyModule_Add(m, "typecodes", tuple) < 0) {
         return -1;
     }