slight cleanup i want in 0.5/0.6

diff --git a/lib/sqlalchemy/topological.py b/lib/sqlalchemy/topological.py
index 306cdfc9005e32d6662660f11f88cedd5ee7abfe..f9b9ad7b3673979a2baef542fb17bb62db0d0e54 100644 (file)
--- a/lib/sqlalchemy/topological.py
+++ b/lib/sqlalchemy/topological.py
@@ -19,6 +19,7 @@ conditions.
 """
 
 from sqlalchemy.exc import CircularDependencyError
+from sqlalchemy import util
 
 __all__ = ['sort', 'sort_with_cycles', 'sort_as_tree']
 
@@ -93,18 +94,14 @@ class _EdgeCollection(object):
     """A collection of directed edges."""
 
     def __init__(self):
-        self.parent_to_children = {}
-        self.child_to_parents = {}
+        self.parent_to_children = util.defaultdict(set)
+        self.child_to_parents = util.defaultdict(set)
 
     def add(self, edge):
         """Add an edge to this collection."""
 
-        (parentnode, childnode) = edge
-        if parentnode not in self.parent_to_children:
-            self.parent_to_children[parentnode] = set()
+        parentnode, childnode = edge
         self.parent_to_children[parentnode].add(childnode)
-        if childnode not in self.child_to_parents:
-            self.child_to_parents[childnode] = set()
         self.child_to_parents[childnode].add(parentnode)
         parentnode.dependencies.add(childnode)
 
@@ -117,13 +114,13 @@ class _EdgeCollection(object):
         (parentnode, childnode) = edge
         self.parent_to_children[parentnode].remove(childnode)
         self.child_to_parents[childnode].remove(parentnode)
-        if len(self.child_to_parents[childnode]) == 0:
+        if not self.child_to_parents[childnode]:
             return childnode
         else:
             return None
 
     def has_parents(self, node):
-        return node in self.child_to_parents and len(self.child_to_parents[node]) > 0
+        return node in self.child_to_parents and bool(self.child_to_parents[node])
 
     def edges_by_parent(self, node):
         if node in self.parent_to_children:

diff --git a/test/base/dependency.py b/test/base/dependency.py
index 1318ef528a5e91aa9344596fb00c67ec16159537..8fcd093b25679611bd87e5fdd14589e7696e38b5 100644 (file)
--- a/test/base/dependency.py
+++ b/test/base/dependency.py
@@ -24,16 +24,16 @@ class DependencySortTest(TestBase):
             assert_tuple(list(tuple), node)
 
         if collection is None:
-            collection = []
+            collection = set()
         items = set()
-        def assert_unique(node):
-            for item in [i for i in node[1] or [node[0]]]:
-                assert item not in items
+        def assert_unique(n):
+            for item in [i for i in n[1] or [n[0]]]:
+                assert item not in items, node
                 items.add(item)
                 if item in collection:
                     collection.remove(item)
-            for c in node[2]:
-                assert_unique(c)
+            for item in n[2]:
+                assert_unique(item)
         assert_unique(node)
         assert len(collection) == 0
 
@@ -171,8 +171,10 @@ class DependencySortTest(TestBase):
         self.assert_sort(tuples, head)
 
     def testcircular3(self):
-        nodes = {}
-        tuples = [('Question', 'Issue'), ('ProviderService', 'Issue'), ('Provider', 'Question'), ('Question', 'Provider'), ('ProviderService', 'Question'), ('Provider', 'ProviderService'), ('Question', 'Answer'), ('Issue', 'Question')]
+        question, issue, providerservice, answer, provider = "Question", "Issue", "ProviderService", "Answer", "Provider"
+
+        tuples = [(question, issue), (providerservice, issue), (provider, question), (question, provider), (providerservice, question), (provider, providerservice), (question, answer), (issue, question)]
+
         head = topological.sort_as_tree(tuples, [], with_cycles=True)
         self.assert_sort(tuples, head)