some example cleanup

1 files changed, 6 insertions, 8 deletions

diff --git a/examples/adjacencytree/basic_tree.py b/examples/adjacencytree/basic_tree.py
index 6a3470fa0..f05f3c3a7 100644
--- a/examples/adjacencytree/basic_tree.py
+++ b/examples/adjacencytree/basic_tree.py
@@ -1,9 +1,8 @@
-from sqlalchemy import *
-import sqlalchemy.util as util
-import string, sys
-
 """a basic Adjacency List model tree."""
 
+from sqlalchemy import *
+from sqlalchemy.util import OrderedDict
+
 metadata = BoundMetaData('sqlite:///', echo=True)
 
 trees = Table('treenodes', metadata,
@@ -12,7 +11,7 @@ trees = Table('treenodes', metadata,
     Column('node_name', String(50), nullable=False),
     )
 
-class NodeList(util.OrderedDict):
+class NodeList(OrderedDict):
     """subclasses OrderedDict to allow usage as a list-based property."""
     def append(self, node):
         self[node.name] = node
@@ -21,7 +20,6 @@ class NodeList(util.OrderedDict):
 
 class TreeNode(object):
     """a rich Tree class which includes path-based operations"""
-    children = NodeList
     def __init__(self, name):
         self.children = NodeList()
         self.name = name
@@ -40,7 +38,7 @@ class TreeNode(object):
     def _getstring(self, level, expand = False):
         s = ('  ' * level) + "%s (%s,%s, %d)" % (self.name, self.id,self.parent_id,id(self)) + '\n'
         if expand:
-            s += string.join([n._getstring(level+1, True) for n in self.children.values()], '')
+            s += ''.join([n._getstring(level+1, True) for n in self.children.values()])
         return s
     def print_nodes(self):
         return self._getstring(0, True)
@@ -49,7 +47,7 @@ mapper(TreeNode, trees, properties=dict(
     id=trees.c.node_id,
     name=trees.c.node_name,
     parent_id=trees.c.parent_node_id,
-    children=relation(TreeNode, cascade="all", backref=backref("parent", foreignkey=trees.c.node_id)),
+    children=relation(TreeNode, cascade="all", backref=backref("parent", foreignkey=trees.c.node_id), collection_class=NodeList),
 ))
 
 print "\n\n\n----------------------------"