Expand Up @@ -6,7 +6,8 @@ from functools import wraps
__all__ = ["asynccontextmanager", "contextmanager", "closing", "nullcontext", "AbstractContextManager", "ContextDecorator", "ExitStack", "AbstractContextManager", "AbstractAsyncContextManager", "ContextDecorator", "ExitStack", "redirect_stdout", "redirect_stderr", "suppress"]

Expand All @@ -30,6 +31,27 @@ def __subclasshook__(cls, C): return NotImplemented

class AbstractAsyncContextManager(abc.ABC):
"""An abstract base class for asynchronous context managers."""
async def __aenter__(self): """Return `self` upon entering the runtime context.""" return self
@abc.abstractmethod async def __aexit__(self, exc_type, exc_value, traceback): """Raise any exception triggered within the runtime context.""" return None
@classmethod def __subclasshook__(cls, C): if cls is AbstractAsyncContextManager: return _collections_abc._check_methods(C, "__aenter__", "__aexit__") return NotImplemented

class ContextDecorator(object): "A base class or mixin that enables context managers to work as decorators."
Expand Down Expand Up @@ -136,7 +158,8 @@ def __exit__(self, type, value, traceback): raise RuntimeError("generator didn't stop after throw()")

class _AsyncGeneratorContextManager(_GeneratorContextManagerBase): class _AsyncGeneratorContextManager(_GeneratorContextManagerBase, AbstractAsyncContextManager): """Helper for @asynccontextmanager."""
async def __aenter__(self): Expand Down