events.py 文件源码

def before_parent_attach(self, target, parent):
        """Called before a :class:`.SchemaItem` is associated with
        a parent :class:`.SchemaItem`.

        :param target: the target object
        :param parent: the parent to which the target is being attached.

        :func:`.event.listen` also accepts a modifier for this event:

        :param propagate=False: When True, the listener function will
         be established for any copies made of the target object,
         i.e. those copies that are generated when
         :meth:`.Table.tometadata` is used.

        """