- apply an import refactoring to the ORM as well

- rework the event system so that event modules load after their
targets, dependencies are reversed
- create an improved strategy lookup system for the ORM
- rework the ORM to have very few import cycles
- move out "importlater" to just util.dependency
- other tricks to cross-populate modules in as clear a way as possible

1 files changed, 18 insertions, 0 deletions

diff --git a/lib/sqlalchemy/sql/base.py b/lib/sqlalchemy/sql/base.py
index e7d83627d..2a3176d04 100644
--- a/lib/sqlalchemy/sql/base.py
+++ b/lib/sqlalchemy/sql/base.py
@@ -152,6 +152,24 @@ class Executable(Generative):
             return None
 
 
+class SchemaEventTarget(object):
+    """Base class for elements that are the targets of :class:`.DDLEvents`
+    events.
+
+    This includes :class:`.SchemaItem` as well as :class:`.SchemaType`.
+
+    """
+
+    def _set_parent(self, parent):
+        """Associate with this SchemaEvent's parent object."""
+
+        raise NotImplementedError()
+
+    def _set_parent_with_dispatch(self, parent):
+        self.dispatch.before_parent_attach(self, parent)
+        self._set_parent(parent)
+        self.dispatch.after_parent_attach(self, parent)
+
 class SchemaVisitor(ClauseVisitor):
     """Define the visiting for ``SchemaItem`` objects."""