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gh-85795: Raise a clear error when super() is used in typing.NamedTuple subclasses #130082

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Merged
JelleZijlstra merged 3 commits into from
Mar 6, 2025
Merged

gh-85795: Raise a clear error when super() is used in typing.NamedTuple subclasses #130082

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ab6131d
Raise a clear error message when `__classcell__` is seen in `typing.N…
johnslavik Mar 4, 2025
8f2ebc8
Raise `TypeError` instead of `RuntimeError` if `__classcell__` is use…
johnslavik Mar 4, 2025
e5539be
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johnslavik Mar 4, 2025
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Raise a clear error message when __classcell__ is seen in `typing.N… 
…amedTuple` subclasses
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@johnslavik
johnslavik committed Mar 4, 2025
commit ab6131d6a4ffbaa7f665d18119f1cf332777b8d3
4 changes: 4 additions & 0 deletions Doc/library/typing.rst
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Expand Up @@ -2359,6 +2359,10 @@ types.
# A functional syntax is also supported
Employee = NamedTuple('Employee', [('name', str), ('id', int)])

.. note::
Using :func:`super` (and the ``__class__`` :term:`closure variable`) in methods of ``NamedTuple`` subclasses
is unsupported and causes a :class:`RuntimeError`.

.. versionchanged:: 3.6
Added support for :pep:`526` variable annotation syntax.

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17 changes: 17 additions & 0 deletions Lib/test/test_typing.py
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Expand Up @@ -8359,6 +8359,23 @@ class VeryAnnoying(metaclass=Meta): pass
class Foo(NamedTuple):
attr = very_annoying

def test_super_explicitly_disallowed(self):
expected_message = (
"uses of super() and __class__ are unsupported "
"in methods of NamedTuple subclasses"
)

with self.assertRaises(RuntimeError, msg=expected_message):
class ThisWontWork(NamedTuple):
def __repr__(self):
return super().__repr__()

with self.assertRaises(RuntimeError, msg=expected_message):
class ThisWontWorkEither(NamedTuple):
@property
def name(self):
return __class__.__name__


class TypedDictTests(BaseTestCase):
def test_basics_functional_syntax(self):
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3 changes: 3 additions & 0 deletions Lib/typing.py
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Expand Up @@ -2961,6 +2961,9 @@ def annotate(format):
class NamedTupleMeta(type):
def __new__(cls, typename, bases, ns):
assert _NamedTuple in bases
if "__classcell__" in ns:
raise RuntimeError(
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"uses of super() and __class__ are unsupported in methods of NamedTuple subclasses")
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for base in bases:
if base is not _NamedTuple and base is not Generic:
raise TypeError(
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3 changes: 3 additions & 0 deletions Misc/NEWS.d/next/Library/2025-02-13-15-10-56.gh-issue-85795.jeXXI9.rst
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@@ -0,0 +1,3 @@
Using :func:`super` and ``__class__`` :term:`closure variable` in
user-defined methods of :class:`typing.NamedTuple` subclasses is now
explicitly prevented at runtime.