Add _repr method to named tuples

Author: bswck

Doc/library/collections.rst

@@ -849,8 +849,9 @@ they add the ability to access fields by name instead of position index.
     Returns a new tuple subclass named *typename*.  The new subclass is used to
     create tuple-like objects that have fields accessible by attribute lookup as
     well as being indexable and iterable.  Instances of the subclass also have a
-    helpful docstring (with typename and field_names) and a helpful :meth:`__repr__`
-    method which lists the tuple contents in a ``name=value`` format.
+    helpful docstring (with typename and field_names) and a helpful :meth:`~somenamedtuple._repr`
+    method, backing the default :meth:`~object.__repr__`, which lists the tuple
+    contents in a ``name=value`` format.
 
     The *field_names* are a sequence of strings such as ``['x', 'y']``.
     Alternatively, *field_names* can be a single string with each fieldname
@@ -985,6 +986,21 @@ field names, the method and attribute names start with an underscore.
        Raise :exc:`TypeError` instead of :exc:`ValueError` for invalid
        keyword arguments.
 
+.. method:: somenamedtuple._repr()
+
+    Return a representation of the named tuple contents in a ``name=value`` format.
+    The default ``__repr__`` implementation uses it to produce the representation.
+
+    .. doctest::
+
+        >>> p = Point(x=11, y=22)
+        >>> p._repr()
+        'Point(x=11, y=22)'
+        >>> p
+        Point(x=11, y=22)
+
+    .. versionadded:: 3.14
+
 .. attribute:: somenamedtuple._fields
 
     Tuple of strings listing the field names.  Useful for introspection

Doc/library/typing.rst

@@ -2341,6 +2341,17 @@ types.
           def __repr__(self) -> str:
               return f'<Employee {self.name}, id={self.id}>'
 
+   To allow extending named tuple's default ``__repr__``, it can be as well accessed with ``self._repr``,
+   as ``super().__repr__`` in a ``NamedTuple`` subclass resolves to ``tuple.__repr__``::
+
+      class Import(NamedTuple):
+          target: str
+
+          def __repr__(self) -> str:
+              # super().__repr__() -> ('target',)
+              # self._repr() -> Import(target='target')
+              return f'<Token {self._repr()}>'  # <Token Import(target='target')>
+
    ``NamedTuple`` subclasses can be generic::
 
       class Group[T](NamedTuple):

Lib/collections/__init__.py

@@ -358,7 +358,7 @@ def __ror__(self, other):
 except ImportError:
     _tuplegetter = lambda index, doc: property(_itemgetter(index), doc=doc)
 
-def namedtuple(typename, field_names, *, rename=False, defaults=None, module=None):
+def namedtuple(typename, field_names, *, rename=False, defaults=None, module=None, _classcell=None):
     """Returns a new subclass of tuple with named fields.
 
     >>> Point = namedtuple('Point', ['x', 'y'])
@@ -469,10 +469,15 @@ def _replace(self, /, **kwds):
     _replace.__doc__ = (f'Return a new {typename} object replacing specified '
                         'fields with new values')
 
-    def __repr__(self):
+    def _repr(self):
         'Return a nicely formatted representation string'
         return self.__class__.__name__ + repr_fmt % self
 
+    def __repr__(self):
+        return self._repr()
+
+    __repr__.__doc__ = _repr.__doc__
+
     def _asdict(self):
         'Return a new dict which maps field names to their values.'
         return _dict(_zip(self._fields, self))
@@ -486,6 +491,7 @@ def __getnewargs__(self):
         __new__,
         _make.__func__,
         _replace,
+        _repr,
         __repr__,
         _asdict,
         __getnewargs__,
@@ -503,6 +509,7 @@ def __getnewargs__(self):
         '_make': _make,
         '__replace__': _replace,
         '_replace': _replace,
+        '_repr': _repr,
         '__repr__': __repr__,
         '_asdict': _asdict,
         '__getnewargs__': __getnewargs__,

Lib/test/test_collections.py

@@ -648,10 +648,12 @@ def test_name_conflicts(self):
     def test_repr(self):
         A = namedtuple('A', 'x')
         self.assertEqual(repr(A(1)), 'A(x=1)')
+        self.assertEqual(A(2)._repr(), 'A(x=2)')
         # repr should show the name of the subclass
         class B(A):
             pass
         self.assertEqual(repr(B(1)), 'B(x=1)')
+        self.assertEqual(B(2)._repr(), 'B(x=2)')
 
     def test_keyword_only_arguments(self):
         # See issue 25628

Lib/test/test_typing.py

@@ -8135,6 +8135,24 @@ class Group(NamedTuple):
         self.assertIs(type(a), Group)
         self.assertEqual(a, (1, [2]))
 
+    def test_overridden_repr(self):
+        class CustomRepresentation(NamedTuple):
+            namedtuple_style: bool
+
+            def __repr__(self):
+                if self.namedtuple_style:
+                    return f"<namedtuple style {self._repr()}>"
+                return f"<tuple style {super().__repr__()}>"
+
+        namedtuple_style_repr = CustomRepresentation(namedtuple_style=True)
+        self.assertEqual(
+            repr(namedtuple_style_repr),
+            "<namedtuple style CustomRepresentation(namedtuple_style=True)>"
+        )
+
+        tuple_style_repr = CustomRepresentation(namedtuple_style=False)
+        self.assertEqual(repr(tuple_style_repr), "<tuple style (False,)>")
+
     def test_namedtuple_keyword_usage(self):
         with self.assertWarnsRegex(
             DeprecationWarning,

Misc/NEWS.d/next/Library/2025-01-27-12-58-51.gh-issue-129343.RMb2ln.rst

@@ -0,0 +1,3 @@
+Added :meth:`~collections.somenamedtuple._repr` method to named tuples for reuse in
+custom :meth:`object.__repr__` implementations in
+:class:`~typing.NamedTuple` subclasses. Contributed by Bartosz Sławecki.