2 files changed, 49 insertions, 2 deletions
diff --git a/Lib/enum.py b/Lib/enum.py
index 775489b..38d95c5 100644
--- a/Lib/enum.py
+++ b/Lib/enum.py
@@ -4,7 +4,7 @@ import sys
 from collections import OrderedDict
 from types import MappingProxyType
 
-__all__ = ['Enum', 'IntEnum']
+__all__ = ['Enum', 'IntEnum', 'unique']
 
 
 class _RouteClassAttributeToGetattr:
@@ -463,3 +463,17 @@ class Enum(metaclass=EnumMeta):
 
 class IntEnum(int, Enum):
     """Enum where members are also (and must be) ints"""
+
+
+def unique(enumeration):
+    """Class decorator for enumerations ensuring unique member values."""
+    duplicates = []
+    for name, member in enumeration.__members__.items():
+        if name != member.name:
+            duplicates.append((name, member.name))
+    if duplicates:
+        alias_details = ', '.join(
+                ["%s -> %s" % (alias, name) for (alias, name) in duplicates])
+        raise ValueError('duplicate values found in %r: %s' %
+                (enumeration, alias_details))
+    return enumeration
diff --git a/Lib/test/test_enum.py b/Lib/test/test_enum.py
index 75b2656..2b87c56 100644
--- a/Lib/test/test_enum.py
+++ b/Lib/test/test_enum.py
@@ -2,7 +2,7 @@ import enum
 import unittest
 from collections import OrderedDict
 from pickle import dumps, loads, PicklingError
-from enum import Enum, IntEnum
+from enum import Enum, IntEnum, unique
 
 # for pickle tests
 try:
@@ -917,5 +917,38 @@ class TestEnum(unittest.TestCase):
         self.assertEqual(Planet.EARTH.value, (5.976e+24, 6.37814e6))
 
 
+class TestUnique(unittest.TestCase):
+
+    def test_unique_clean(self):
+        @unique
+        class Clean(Enum):
+            one = 1
+            two = 'dos'
+            tres = 4.0
+        @unique
+        class Cleaner(IntEnum):
+            single = 1
+            double = 2
+            triple = 3
+
+    def test_unique_dirty(self):
+        with self.assertRaisesRegex(ValueError, 'tres.*one'):
+            @unique
+            class Dirty(Enum):
+                one = 1
+                two = 'dos'
+                tres = 1
+        with self.assertRaisesRegex(
+                ValueError,
+                'double.*single.*turkey.*triple',
+                ):
+            @unique
+            class Dirtier(IntEnum):
+                single = 1
+                double = 1
+                triple = 3
+                turkey = 3
+
+
 if __name__ == '__main__':
     unittest.main()