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gh-145118: Add frozendict support to type() #145124

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gh-145118: Add frozendict support to type() #145124

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69b8521
Add `frozendict` support to `str.maketrans()` and `type()`
StanFromIreland Feb 22, 2026
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StanFromIreland Feb 22, 2026
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6 changes: 6 additions & 0 deletions Lib/test/test_builtin.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2993,6 +2993,12 @@ def test_type_doc(self):
A.__doc__ = doc
self.assertEqual(A.__doc__, doc)

def test_type_frozendict(self):
A = type('A', (), frozendict({'x': 4, 'y': 2}))
self.assertEqual(A.x, 4)
self.assertEqual(A.y, 2)
self.assertEqual(A.__name__, 'A')

def test_bad_args(self):
with self.assertRaises(TypeError):
type()
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1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Core_and_Builtins/2026-02-22-19-05-03.gh-issue-145118.bU6Sic.rst
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@@ -0,0 +1 @@
:func:`type` now accepts :class:`frozendict` as an argument.
28 changes: 23 additions & 5 deletions Objects/typeobject.c
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Expand Up @@ -4872,9 +4872,21 @@ type_new_get_slots(type_new_ctx *ctx, PyObject *dict)
static PyTypeObject*
type_new_init(type_new_ctx *ctx)
{
PyObject *dict = PyDict_Copy(ctx->orig_dict);
if (dict == NULL) {
goto error;
PyObject *dict;
if (PyFrozenDict_Check(ctx->orig_dict)) {
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@eendebakpt eendebakpt Feb 22, 2026 •
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Note: this code path is needed because PyDict_Copy would return a frozendict, see

cpython/Objects/dictobject.c

Line 4257 in fd01372

int frozendict = PyFrozenDict_Check(o);
(this is not explicitly documented, I will make a new issue/pr for that).

dict = PyDict_New();
if (dict == NULL) {
goto error;
}
if (PyDict_Merge(dict, ctx->orig_dict, 1) < 0) {
goto error;
}
}
else {
dict = PyDict_Copy(ctx->orig_dict);
if (dict == NULL) {
goto error;
}
}

if (type_new_get_slots(ctx, dict) < 0) {
Expand Down Expand Up @@ -5037,13 +5049,19 @@ type_new(PyTypeObject *metatype, PyObject *args, PyObject *kwds)

/* Parse arguments: (name, bases, dict) */
PyObject *name, *bases, *orig_dict;
if (!PyArg_ParseTuple(args, "UO!O!:type.__new__",
if (!PyArg_ParseTuple(args, "UO!O:type.__new__",
&name,
&PyTuple_Type, &bases,
&PyDict_Type, &orig_dict))
&orig_dict))
{
return NULL;
}
if (!PyAnyDict_Check(orig_dict)) {
PyErr_Format(PyExc_TypeError,
"type.__new__() argument 3 must be dict, not %T",
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@eendebakpt eendebakpt Feb 22, 2026 •
edited
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Suggested change
"type.__new__() argument 3 must be dict, not %T",
"type.__new__() argument 3 must be dict or frozendict, not %T",

For consideration, not sure I would make the change myself.

(and whatever the outcome: be consistent with maketrans below)

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@StanFromIreland StanFromIreland Feb 22, 2026

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Other error messages weren't updated like this, no?

orig_dict);
return NULL;
}

type_new_ctx ctx = {
.metatype = metatype,
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