python · serhiy-storchaka · Feb 10, 2024 · Mar 20, 2023 · Mar 20, 2023 · Mar 20, 2023
diff --git a/Lib/fractions.py b/Lib/fractions.py
@@ -611,29 +611,33 @@ class doesn't subclass a concrete type, there's no
 
         """
         def forward(a, b):
-            if isinstance(b, Fraction):
-                return monomorphic_operator(a, b)
-            elif isinstance(b, int):
-                return monomorphic_operator(a, Fraction(b))
-            elif isinstance(b, float):
-                return fallback_operator(float(a), b)
-            elif isinstance(b, complex):
-                return fallback_operator(complex(a), b)
-            else:
-                return NotImplemented
+            try:
+                if isinstance(b, Fraction):
+                    return monomorphic_operator(a, b)
+                elif isinstance(b, int):
+                    return monomorphic_operator(a, Fraction(b))
+                elif isinstance(b, float):
+                    return fallback_operator(float(a), b)
+                elif isinstance(b, complex):
+                    return fallback_operator(complex(a), b)
+            except TypeError:
+                pass
+            return NotImplemented
         forward.__name__ = '__' + fallback_operator.__name__ + '__'
         forward.__doc__ = monomorphic_operator.__doc__
 
         def reverse(b, a):
-            if isinstance(a, numbers.Rational):
-                # Includes ints.
-                return monomorphic_operator(Fraction(a), b)
-            elif isinstance(a, numbers.Real):
-                return fallback_operator(float(a), float(b))
-            elif isinstance(a, numbers.Complex):
-                return fallback_operator(complex(a), complex(b))
-            else:
-                return NotImplemented
+            try:
+                if isinstance(a, numbers.Rational):
+                    # Includes ints.
+                    return monomorphic_operator(Fraction(a), b)
+                elif isinstance(a, numbers.Real):
+                    return fallback_operator(float(a), float(b))
+                elif isinstance(a, numbers.Complex):
+                    return fallback_operator(complex(a), complex(b))
+            except TypeError:
+                pass
+            return NotImplemented
         reverse.__name__ = '__r' + fallback_operator.__name__ + '__'
         reverse.__doc__ = monomorphic_operator.__doc__
 

diff --git a/Lib/test/test_fractions.py b/Lib/test/test_fractions.py
@@ -1220,6 +1220,29 @@ def test_invalid_formats(self):
                 with self.assertRaises(ValueError):
                     format(fraction, spec)
 
+    def test_traceback_in_mod_and_floordiv_with_complex_objects(self):
+        # See issue-102840 for more details.
+
+        a = F(1, 2)
+        b = 1j
+        mod = lambda x, y: x % y
+        floordiv = lambda x, y: x // y
+        message = "unsupported operand type(s) for %s: %s and %s"
+        # test forward
+        self.assertRaisesMessage(TypeError,
+                                 message % ("%", "'Fraction'", "'complex'"),
+                                 mod, a, b)
+        self.assertRaisesMessage(TypeError,
+                                 message % ("//", "'Fraction'", "'complex'"),
+                                 floordiv, a, b)
+        # test reverse
+        self.assertRaisesMessage(TypeError,
+                                 message % ("%", "'complex'", "'Fraction'"),
+                                 mod, b, a)
+        self.assertRaisesMessage(TypeError,
+                                 message % ("//", "'complex'", "'Fraction'"),
+                                 floordiv, b, a)
+
 
 if __name__ == '__main__':
     unittest.main()