gh-144191: Dataclasses single field ordering

Lib/dataclasses.py

@@ -1180,21 +1180,27 @@ def _process_class(cls, init, repr, eq, order, unsafe_hash, frozen,
     if order:
         # Create and set the ordering methods.
         flds = [f for f in field_list if f.compare]
-        self_tuple = _tuple_str('self', flds)
-        other_tuple = _tuple_str('other', flds)
+        match flds:
+            # Special-case single field comparisons. See GH-144191.
+            case [single_fld]:
+                self_expr = f'self.{single_fld.name}'
+                other_expr = f'other.{single_fld.name}'
+            case _:
+                self_expr = _tuple_str('self', flds)
+                other_expr = _tuple_str('other', flds)
         for name, op in [('__lt__', '<'),
                          ('__le__', '<='),
                          ('__gt__', '>'),
                          ('__ge__', '>='),
                          ]:
             # Create a comparison function.  If the fields in the object are
-            # named 'x' and 'y', then self_tuple is the string
-            # '(self.x,self.y)' and other_tuple is the string
+            # named 'x' and 'y', then self_expr is the string
+            # '(self.x,self.y)' and other_expr is the string
             # '(other.x,other.y)'.
             func_builder.add_fn(name,
                             ('self', 'other'),
                             [ '  if other.__class__ is self.__class__:',
-                             f'   return {self_tuple}{op}{other_tuple}',
+                             f'   return {self_expr}{op}{other_expr}',
                               '  return NotImplemented'],
                             overwrite_error='Consider using functools.total_ordering')
 

Lib/test/test_dataclasses/__init__.py

@@ -406,6 +406,16 @@ class C:
         self.assertGreaterEqual(C(1), C(0))
         self.assertGreaterEqual(C(1), C(1))
 
+        @dataclass(order=True)
+        class C2:
+            x: int
+            y: int = field(compare=False)
+
+        self.assertLess(C2(0, 10), C2(1, -5))
+        self.assertLessEqual(C2(1, 10), C2(1, -5))
+        self.assertGreater(C2(2, -1), C2(1, 999))
+        self.assertGreaterEqual(C2(1, 10), C2(1, -5))
+
     def test_simple_compare(self):
         # Ensure that order=False is the default.
         @dataclass

Misc/NEWS.d/next/Library/2026-01-26-14-51-22.gh-issue-144191.jHXZrc.rst

@@ -0,0 +1 @@
+Dataclass ordering methods were adjusted to simplify comparisons for classes with a single comparison field, aligning the generated behaviour more closely with hand-written comparison logic.