Backmerge -r59233:59232

Guido said:
Please roll this back.  The error message you added is inappropriate
when the parameter to a legitimate register() call is omitted, e.g.

collections.Sequence.register()

diff --git a/Lib/abc.py b/Lib/abc.py
index 30bb6b00ba68feb95f090f03a78d4b4bf7487882..54dc8e2d9753514784c36ec5cf87ea3fe816e2a7 100644 (file)
--- a/Lib/abc.py
+++ b/Lib/abc.py
@@ -137,11 +137,8 @@ class ABCMeta(type):
         cls._abc_negative_cache_version = ABCMeta._abc_invalidation_counter
         return cls
 
-    def register(cls, subclass=None):
+    def register(cls, subclass):
         """Register a virtual subclass of an ABC."""
-        if subclass is None:
-            raise TypeError("register() cannot be called on an ABCMeta "
-                "subclass, use class Example(metaclass=abc.ABCMeta) instead.")
         if not isinstance(cls, type):
             raise TypeError("Can only register classes")
         if issubclass(subclass, cls):

diff --git a/Lib/test/test_abc.py b/Lib/test/test_abc.py
index a04b2715156e2cf61bfb3998ee8fb18a14c10508..e6c84154fe1f089c3a6606038eb882f24f458948 100644 (file)
--- a/Lib/test/test_abc.py
+++ b/Lib/test/test_abc.py
@@ -146,13 +146,6 @@ class TestABC(unittest.TestCase):
         C()
         self.assertEqual(B.counter, 1)
 
-    def test_error_on_subclass(self):
-        class A(abc.ABCMeta):
-            pass
-        class B:
-            pass
-        self.assertRaises(TypeError, A.register, B)
-
 
 def test_main():
     test_support.run_unittest(TestABC)