pep-484: asyncio

in this patch the asyncio/events.py module, which
existed only to raise errors when trying to attach event
listeners, is removed, as we were already coding an asyncio-specific
workaround in upstream Pool / Session to raise this error,
just moved the error out to the target and did the same thing
for Engine.

We also add an async_sessionmaker class.  The initial rationale
here is because sessionmaker() is hardcoded to Session subclasses,
and there's not a way to get the use case of
sessionmaker(class_=AsyncSession) to type correctly without changing
the sessionmaker() symbol itself to be a function and not a class,
which gets too complicated for what this is. Additionally,
_SessionClassMethods has only three methods on it, one of which
is not usable with asyncio (close_all()), the others
not generally used from the session class.

Change-Id: I064a5fa5d91cc8d5bbe9597437536e37b4e801fe

1 files changed, 3 insertions, 1 deletions

diff --git a/lib/sqlalchemy/engine/result.py b/lib/sqlalchemy/engine/result.py
index 880bd8d4c..11998e718 100644
--- a/lib/sqlalchemy/engine/result.py
+++ b/lib/sqlalchemy/engine/result.py
@@ -536,7 +536,9 @@ class ResultInternal(InPlaceGenerative, Generic[_R]):
         return interim_rows
 
     @HasMemoized_ro_memoized_attribute
-    def _onerow_getter(self) -> Callable[..., Union[_NoRow, _R]]:
+    def _onerow_getter(
+        self,
+    ) -> Callable[..., Union[Literal[_NoRow._NO_ROW], _R]]:
         make_row = self._row_getter
 
         post_creational_filter = self._post_creational_filter