- [feature] Improvements to event listening for

    mapped classes allows that unmapped classes
    can be specified for instance- and mapper-events.
    The established events will be automatically
    set up on subclasses of that class when the
    propagate=True flag is passed, and the
    events will be set up for that class itself
    if and when it is ultimately mapped.
    [ticket:2585]

  - [bug] The instrumentation events class_instrument(),
    class_uninstrument(), and attribute_instrument()
    will now fire off only for descendant classes
    of the class assigned to listen().  Previously,
    an event listener would be assigned to listen
    for all classes in all cases regardless of the
    "target" argument passed.  [ticket:2590]

1 files changed, 7 insertions, 4 deletions

diff --git a/lib/sqlalchemy/event.py b/lib/sqlalchemy/event.py
index 633cb96f8..c702d9d34 100644
--- a/lib/sqlalchemy/event.py
+++ b/lib/sqlalchemy/event.py
@@ -148,6 +148,12 @@ class _Dispatch(object):
             getattr(self, ls.name).\
                 for_modify(self)._update(ls, only_propagate=only_propagate)
 
+    @util.hybridmethod
+    def _clear(self):
+        for attr in dir(self):
+            if _is_event_name(attr):
+                getattr(self, attr).for_modify(self).clear()
+
 def _event_descriptors(target):
     return [getattr(target, k) for k in dir(target) if _is_event_name(k)]
 
@@ -170,7 +176,6 @@ def _create_dispatcher_class(cls, classname, bases, dict_):
     cls.dispatch = dispatch_cls = type("%sDispatch" % classname,
                                         (dispatch_base, ), {})
     dispatch_cls._listen = cls._listen
-    dispatch_cls._clear = cls._clear
 
     for k in dict_:
         if _is_event_name(k):
@@ -218,9 +223,7 @@ class Events(object):
 
     @classmethod
     def _clear(cls):
-        for attr in dir(cls.dispatch):
-            if _is_event_name(attr):
-                getattr(cls.dispatch, attr).clear()
+        cls.dispatch._clear()
 
 class _DispatchDescriptor(object):
     """Class-level attributes on :class:`._Dispatch` classes."""