- added util.portable_instancemethod to provide a quick way to make an instancemethod "serializable"

- SchemaType and subclasses Boolean, Enum are now serializable,
including their ddl listener and other event callables.
[ticket:1694] [ticket:1698]
- AddConstraint/DropConstraint use the wrapper for _create_rule
- added test coverage for AddConstraint override of _create_rule

1 files changed, 12 insertions, 0 deletions

diff --git a/lib/sqlalchemy/util.py b/lib/sqlalchemy/util.py
index 07b8269a9..873243de1 100644
--- a/lib/sqlalchemy/util.py
+++ b/lib/sqlalchemy/util.py
@@ -453,6 +453,18 @@ def unbound_method_to_callable(func_or_cls):
     else:
         return func_or_cls
 
+class portable_instancemethod(object):
+    """Turn an instancemethod into a (parent, name) pair
+    to produce a serializable callable.
+    
+    """
+    def __init__(self, meth):
+        self.target = meth.im_self
+        self.name = meth.__name__
+
+    def __call__(self, *arg, **kw):
+        return getattr(self.target, self.name)(*arg, **kw)
+        
 def class_hierarchy(cls):
     """Return an unordered sequence of all classes related to cls.