Allow usage of SomeABC.register as a class decorator. Patch by Edoardo Spadolini (#10868).
diff --git a/Lib/abc.py b/Lib/abc.py
index a6c2dc4..40f88b9 100644
--- a/Lib/abc.py
+++ b/Lib/abc.py
@@ -133,11 +133,14 @@
return cls
def register(cls, subclass):
- """Register a virtual subclass of an ABC."""
+ """Register a virtual subclass of an ABC.
+
+ Returns the subclass, to allow usage as a class decorator.
+ """
if not isinstance(subclass, type):
raise TypeError("Can only register classes")
if issubclass(subclass, cls):
- return # Already a subclass
+ return subclass # Already a subclass
# Subtle: test for cycles *after* testing for "already a subclass";
# this means we allow X.register(X) and interpret it as a no-op.
if issubclass(cls, subclass):
@@ -145,6 +148,7 @@
raise RuntimeError("Refusing to create an inheritance cycle")
cls._abc_registry.add(subclass)
ABCMeta._abc_invalidation_counter += 1 # Invalidate negative cache
+ return subclass
def _dump_registry(cls, file=None):
"""Debug helper to print the ABC registry."""