Issue #24400: Resurrect inspect.isawaitable()
collections.abc.Awaitable and collections.abc.Coroutine no longer
use __instancecheck__ hook to detect generator-based coroutines.
inspect.isawaitable() can be used to detect generator-based coroutines
and to distinguish them from regular generator objects.
diff --git a/Lib/_collections_abc.py b/Lib/_collections_abc.py
index ba6a9b8..f89bb6f 100644
--- a/Lib/_collections_abc.py
+++ b/Lib/_collections_abc.py
@@ -81,22 +81,7 @@
return NotImplemented
-class _AwaitableMeta(ABCMeta):
-
- def __instancecheck__(cls, instance):
- # This hook is needed because we can't add
- # '__await__' method to generator objects, and
- # we can't register GeneratorType on Awaitable.
- # NB: 0x100 = CO_ITERABLE_COROUTINE
- # (We don't want to import 'inspect' module, as
- # a dependency for 'collections.abc')
- if (instance.__class__ is generator and
- instance.gi_code.co_flags & 0x100):
- return True
- return super().__instancecheck__(instance)
-
-
-class Awaitable(metaclass=_AwaitableMeta):
+class Awaitable(metaclass=ABCMeta):
__slots__ = ()
diff --git a/Lib/inspect.py b/Lib/inspect.py
index f48769e..45679cf 100644
--- a/Lib/inspect.py
+++ b/Lib/inspect.py
@@ -207,6 +207,13 @@
"""Return true if the object is a coroutine."""
return isinstance(object, types.CoroutineType)
+def isawaitable(object):
+ """Return true is object can be passed to an ``await`` expression."""
+ return (isinstance(object, types.CoroutineType) or
+ isinstance(object, types.GeneratorType) and
+ object.gi_code.co_flags & CO_ITERABLE_COROUTINE or
+ isinstance(object, collections.abc.Awaitable))
+
def istraceback(object):
"""Return true if the object is a traceback.
diff --git a/Lib/test/test_collections.py b/Lib/test/test_collections.py
index ab2b733..fbaf712 100644
--- a/Lib/test/test_collections.py
+++ b/Lib/test/test_collections.py
@@ -511,8 +511,10 @@
self.assertTrue(issubclass(type(x), Awaitable))
c = coro()
- self.assertIsInstance(c, Awaitable)
- c.close() # awoid RuntimeWarning that coro() was not awaited
+ # Iterable coroutines (generators with CO_ITERABLE_COROUTINE
+ # flag don't have '__await__' method, hence can't be instances
+ # of Awaitable. Use inspect.isawaitable to detect them.
+ self.assertNotIsInstance(c, Awaitable)
c = new_coro()
self.assertIsInstance(c, Awaitable)
@@ -559,8 +561,10 @@
self.assertTrue(issubclass(type(x), Awaitable))
c = coro()
- self.assertIsInstance(c, Coroutine)
- c.close() # awoid RuntimeWarning that coro() was not awaited
+ # Iterable coroutines (generators with CO_ITERABLE_COROUTINE
+ # flag don't have '__await__' method, hence can't be instances
+ # of Coroutine. Use inspect.isawaitable to detect them.
+ self.assertNotIsInstance(c, Coroutine)
c = new_coro()
self.assertIsInstance(c, Coroutine)
diff --git a/Lib/test/test_inspect.py b/Lib/test/test_inspect.py
index ab22c7d..a02f2e1 100644
--- a/Lib/test/test_inspect.py
+++ b/Lib/test/test_inspect.py
@@ -151,6 +151,29 @@
coro.close(); gen_coro.close() # silence warnings
+ def test_isawaitable(self):
+ def gen(): yield
+ self.assertFalse(inspect.isawaitable(gen()))
+
+ coro = coroutine_function_example(1)
+ gen_coro = gen_coroutine_function_example(1)
+
+ self.assertTrue(inspect.isawaitable(coro))
+ self.assertTrue(inspect.isawaitable(gen_coro))
+
+ class Future:
+ def __await__():
+ pass
+ self.assertTrue(inspect.isawaitable(Future()))
+ self.assertFalse(inspect.isawaitable(Future))
+
+ class NotFuture: pass
+ not_fut = NotFuture()
+ not_fut.__await__ = lambda: None
+ self.assertFalse(inspect.isawaitable(not_fut))
+
+ coro.close(); gen_coro.close() # silence warnings
+
def test_isroutine(self):
self.assertTrue(inspect.isroutine(mod.spam))
self.assertTrue(inspect.isroutine([].count))
diff --git a/Lib/test/test_types.py b/Lib/test/test_types.py
index ba8a1b9..738588e 100644
--- a/Lib/test/test_types.py
+++ b/Lib/test/test_types.py
@@ -1447,6 +1447,19 @@
with self.assertRaisesRegex(Exception, 'ham'):
wrapper.throw(Exception, Exception('ham'))
+ def test_returning_itercoro(self):
+ @types.coroutine
+ def gen():
+ yield
+
+ gencoro = gen()
+
+ @types.coroutine
+ def foo():
+ return gencoro
+
+ self.assertIs(foo(), gencoro)
+
def test_genfunc(self):
def gen(): yield
self.assertIs(types.coroutine(gen), gen)
@@ -1457,9 +1470,6 @@
g = gen()
self.assertTrue(g.gi_code.co_flags & inspect.CO_ITERABLE_COROUTINE)
self.assertFalse(g.gi_code.co_flags & inspect.CO_COROUTINE)
- self.assertIsInstance(g, collections.abc.Coroutine)
- self.assertIsInstance(g, collections.abc.Awaitable)
- g.close() # silence warning
self.assertIs(types.coroutine(gen), gen)
diff --git a/Lib/types.py b/Lib/types.py
index 8c5fc65..48891cd 100644
--- a/Lib/types.py
+++ b/Lib/types.py
@@ -241,12 +241,12 @@
@_functools.wraps(func)
def wrapped(*args, **kwargs):
coro = func(*args, **kwargs)
- if coro.__class__ is CoroutineType:
- # 'coro' is a native coroutine object.
+ if (coro.__class__ is CoroutineType or
+ coro.__class__ is GeneratorType and coro.gi_code.co_flags & 0x100):
+ # 'coro' is a native coroutine object or an iterable coroutine
return coro
- if (coro.__class__ is GeneratorType or
- (isinstance(coro, _collections_abc.Generator) and
- not isinstance(coro, _collections_abc.Coroutine))):
+ if (isinstance(coro, _collections_abc.Generator) and
+ not isinstance(coro, _collections_abc.Coroutine)):
# 'coro' is either a pure Python generator iterator, or it
# implements collections.abc.Generator (and does not implement
# collections.abc.Coroutine).