- Fixed regression where using a ``functools.partial()`` with the event

system would cause a recursion overflow due to usage of inspect.getargspec()
on it in order to detect a legacy calling signature for certain events,
and apparently there's no way to do this with a partial object.  Instead
we skip the legacy check and assume the modern style; the check itself
now only occurs for the SessionEvents.after_bulk_update and
SessionEvents.after_bulk_delete events.  Those two events will require
the new signature style if assigned to a "partial" event listener.
[ticket:2905]

1 files changed, 7 insertions, 2 deletions

diff --git a/lib/sqlalchemy/event/attr.py b/lib/sqlalchemy/event/attr.py
index 690ebce08..f0fff5ca4 100644
--- a/lib/sqlalchemy/event/attr.py
+++ b/lib/sqlalchemy/event/attr.py
@@ -62,10 +62,15 @@ class _DispatchDescriptor(RefCollection):
         self._empty_listeners = weakref.WeakKeyDictionary()
 
     def _adjust_fn_spec(self, fn, named):
-        argspec = util.get_callable_argspec(fn, no_self=True)
         if named:
             fn = self._wrap_fn_for_kw(fn)
-        fn = legacy._wrap_fn_for_legacy(self, fn, argspec)
+        if self.legacy_signatures:
+            try:
+                argspec = util.get_callable_argspec(fn, no_self=True)
+            except ValueError:
+                pass
+            else:
+                fn = legacy._wrap_fn_for_legacy(self, fn, argspec)
         return fn
 
     def _wrap_fn_for_kw(self, fn):