- Removal of event listeners is now implemented. The feature is

provided via the :func:`.event.remove` function.
[ticket:2268]
- reorganization of event.py module into a package; with the addition of the
docstring work as well as the new registry for removal, there's a lot more code now.
the package separates concerns and provides a top-level doc for each subsection
of functionality
- the remove feature works by providing the EventKey object which associates
the user-provided arguments to listen() with a global, weak-referencing registry.
This registry stores a collection of _ListenerCollection and _DispatchDescriptor
objects associated with each set of arguments, as well as the wrapped function
which was applied to that collection.  The EventKey can then be recreated for
a removal, all the _ListenerCollection and _DispatchDescriptor objects are located,
and the correct wrapped function is removed from each one.

1 files changed, 5 insertions, 2 deletions

diff --git a/lib/sqlalchemy/events.py b/lib/sqlalchemy/events.py
index 4fb997b9c..555d3b4a1 100644
--- a/lib/sqlalchemy/events.py
+++ b/lib/sqlalchemy/events.py
@@ -450,7 +450,10 @@ class ConnectionEvents(event.Events):
     _target_class_doc = "SomeEngine"
 
     @classmethod
-    def _listen(cls, target, identifier, fn, retval=False):
+    def _listen(cls, event_key, retval=False):
+        target, identifier, fn = \
+            event_key.dispatch_target, event_key.identifier, event_key.fn
+
         target._has_events = True
 
         if not retval:
@@ -479,7 +482,7 @@ class ConnectionEvents(event.Events):
                     "'before_cursor_execute' engine "
                     "event listeners accept the 'retval=True' "
                     "argument.")
-        event.Events._listen(target, identifier, fn)
+        event_key.with_wrapper(fn).base_listen()
 
     def before_execute(self, conn, clauseelement, multiparams, params):
         """Intercept high level execute() events, receiving uncompiled