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gh-136492: Add FrameLocalsProxy to types #136546

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78b842c
Expose FrameLocalsProxy in types and _types
ZeroIntensity Jul 11, 2025
e2ddcbe
Add a test case.
ZeroIntensity Jul 11, 2025
22e056d
Add a documentation entry.
ZeroIntensity Jul 11, 2025
b8fd733
Use the 'type' suffix.
ZeroIntensity Jul 11, 2025
abbe1d3
Add a whatsnew entry.
ZeroIntensity Jul 11, 2025
753c9bc
Add blurb.
ZeroIntensity Jul 11, 2025
b087d9b
Fix the tests.
ZeroIntensity Jul 11, 2025
1971a14
Sort the name alphabetically.
ZeroIntensity Jul 11, 2025
fdeb2d0
Sort alphabetically in _types.
ZeroIntensity Jul 11, 2025
c8600b9
Move whatsnew section.
ZeroIntensity Jul 11, 2025
70cc4db
Somewhat fix the tests.
ZeroIntensity Jul 11, 2025
fee5256
Reduce the diff.
ZeroIntensity Jul 11, 2025
a110148
Use a workaround for the tests.
ZeroIntensity Jul 11, 2025
929f81e
Move PEP note and remove locals() reference.
ZeroIntensity Jul 11, 2025
fb710eb
Update Doc/whatsnew/3.15.rst
ZeroIntensity Jul 12, 2025
5923263
Add a signature for FrameLocalsProxy()
ZeroIntensity Jul 12, 2025
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11 changes: 11 additions & 0 deletions Doc/library/types.rst
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Expand Up @@ -333,6 +333,17 @@ Standard names are defined for the following types:
:attr:`tb.tb_frame <traceback.tb_frame>` if ``tb`` is a traceback object.


.. data:: FrameLocalsProxyType

The type of frame locals proxy objects, as found on the
:attr:`frame.f_locals` attribute.

.. versionadded:: next

.. seealso::
:pep:`667`


.. data:: GetSetDescriptorType

The type of objects defined in extension modules with ``PyGetSetDef``, such
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7 changes: 7 additions & 0 deletions Doc/whatsnew/3.15.rst
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Expand Up @@ -278,6 +278,13 @@ tarfile
and :cve:`2025-4435`.)


types
------

* Added :data:`types.FrameLocalsProxyType` for representing the type of
the :attr:`frame.f_locals` attribute, as described in :pep:`667`.


zlib
----

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1 change: 1 addition & 0 deletions Lib/test/test_inspect/test_inspect.py
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Expand Up @@ -5786,6 +5786,7 @@ def test_types_module_has_signatures(self):
'AsyncGeneratorType': {'athrow'},
'CoroutineType': {'throw'},
'GeneratorType': {'throw'},
'FrameLocalsProxyType': {'setdefault', 'pop', 'get'}
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This should be fixable by converting these methods to Argument Clinic or manually adding a docstring with a signature.

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To be clear I'm not asking you to necessarily fix this, though I think it'd be nice to reduce the size of the denylist in this test.

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I agree that we should fix these, but would you like it to be done in this PR? Same goes for the tp_doc on FrameLocalsProxy.

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Up to you! I feel it makes sense though that if we expose this publicly, we should also give it a docstring.

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I'll add the tp_doc in this PR, but I think the AC changes would be better for a follow-up.

}
self._test_module_has_signatures(types,
unsupported_signature=unsupported_signature,
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6 changes: 6 additions & 0 deletions Lib/test/test_types.py
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Expand Up @@ -58,6 +58,7 @@ def test_names(self):
'MethodDescriptorType', 'MethodType', 'MethodWrapperType',
'ModuleType', 'NoneType', 'NotImplementedType', 'SimpleNamespace',
'TracebackType', 'UnionType', 'WrapperDescriptorType',
'FrameLocalsProxyType'
}
self.assertEqual(all_names, set(c_types.__all__))
self.assertEqual(all_names - c_only_names, set(py_types.__all__))
Expand Down Expand Up @@ -711,6 +712,11 @@ def call(part):
"""
assert_python_ok("-c", code)

def test_frame_locals_proxy(self):
frame = inspect.currentframe()
self.assertIsNotNone(frame)
self.assertIsInstance(frame.f_locals, types.FrameLocalsProxyType)


class UnionTests(unittest.TestCase):

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1 change: 1 addition & 0 deletions Lib/types.py
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Expand Up @@ -69,6 +69,7 @@ def _m(self): pass
EllipsisType = type(Ellipsis)
NoneType = type(None)
NotImplementedType = type(NotImplemented)
FrameLocalsProxyType = (lambda: type(sys._getframe().f_locals))()
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Introspecting this class currently would make you think it is builtins.FrameLocalProxy:

>>> FrameLocalsProxyType = (lambda: type(sys._getframe().f_locals))()
>>> FrameLocalsProxyType.__module__
'builtins'
>>> FrameLocalsProxyType.__name__
'FrameLocalsProxy'

What do you think about changing its tp_name to types.FrameLocalsProxyType, so that the runtime __module__ and __name__ attributes are consistent with the place where you can actually find it? This is what types.SimpleNamespace already does.

Personally I'd ideally want to do this for all the types.* types, but there are compatibility concerns for some. Here though, given that the type is relatively new and private, maybe we can get away with changing its name and module.

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That makes sense to me, any objections @gaogaotiantian?

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I mean if we are keeping the behavior of almost all the types in types, the new "correct" one would be the confusing one. FrameType has the name frame, CellType has the name cell, CodeType has the name code. The closest one MappingProxyType even has the name mappingproxy. I think if this is not super critical, maybe sticking to the old tradition is more consistent to users.

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I feel the fact that the __module__ is inconsistent on so many existing types shouldn't be an argument to keep doing it wrong.

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I'm fine with __module__, my argument was more about __name__.

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The problem is that __module__ is set from the tp_name. A compromise could be to name it types.FrameLocalsProxy, but that deviates from the *Type convention that currently exists in types.


# CapsuleType cannot be accessed from pure Python,
# so there is no fallback definition.
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1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Library/2025-07-11-10-23-44.gh-issue-136492.BVi5h0.rst
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@@ -0,0 +1 @@
Add :data:`~types.FrameLocalsProxyType` to the :mod:`types` module.
1 change: 1 addition & 0 deletions Modules/_typesmodule.c
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Expand Up @@ -28,6 +28,7 @@ _types_exec(PyObject *m)
EXPORT_STATIC_TYPE("CoroutineType", PyCoro_Type);
EXPORT_STATIC_TYPE("EllipsisType", PyEllipsis_Type);
EXPORT_STATIC_TYPE("FrameType", PyFrame_Type);
EXPORT_STATIC_TYPE("FrameLocalsProxyType", PyFrameLocalsProxy_Type);
EXPORT_STATIC_TYPE("FunctionType", PyFunction_Type);
EXPORT_STATIC_TYPE("GeneratorType", PyGen_Type);
EXPORT_STATIC_TYPE("GenericAlias", Py_GenericAliasType);
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10 changes: 10 additions & 0 deletions Objects/frameobject.c
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Expand Up @@ -913,6 +913,15 @@ static PyMethodDef framelocalsproxy_methods[] = {
{NULL, NULL} /* sentinel */
};

PyDoc_STRVAR(framelocalsproxy_doc,
"FrameLocalsProxy($frame)\n"
"--\n"
"\n"
"Create a write-through view of the locals dictionary for a frame.\n"
"\n"
" frame\n"
" the frame object to wrap.");

PyTypeObject PyFrameLocalsProxy_Type = {
PyVarObject_HEAD_INIT(&PyType_Type, 0)
.tp_name = "FrameLocalsProxy",
Expand All @@ -933,6 +942,7 @@ PyTypeObject PyFrameLocalsProxy_Type = {
.tp_alloc = PyType_GenericAlloc,
.tp_new = framelocalsproxy_new,
.tp_free = PyObject_GC_Del,
.tp_doc = framelocalsproxy_doc
};

PyObject *
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