The root factory may now return an object which implements ``ITraverser`` directly. In this case, no adaptation is done before traversal. This feature is added such that a routes factory can implement its own traversal logic without establishing an artificial context only to get a hook into the traversal machinery.

4 files changed, 50 insertions, 6 deletions

diff --git a/CHANGES.txt b/CHANGES.txt
index b4c04304e..b112a996a 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -4,6 +4,10 @@ Next release
 Features
 --------
 
+- The root factory may now return an object which implements
+  ``ITraverser`` directly. In this case, no adaptation is done before
+  traversal.
+
 - Add ``path_info`` view configuration predicate.
 
 - ``paster bfgshell`` now supports IPython if it's available for
diff --git a/docs/narr/hooks.rst b/docs/narr/hooks.rst
index d2020af0d..6babeace0 100644
--- a/docs/narr/hooks.rst
+++ b/docs/narr/hooks.rst
@@ -278,6 +278,9 @@ when the application :term:`root factory` returned an instance of the
 ``myapp.models.MyRoot`` object.  Otherwise it would use the default
 :mod:`repoze.bfg` traverser to do traversal.
 
+Note that the root object may itself implement ``ITraverser`` in which
+case adaptation is skipped.
+
 Example implementations of alternate traversers can be found "in the
 wild" within `repoze.bfg.traversalwrapper
 <http://pypi.python.org/pypi/repoze.bfg.traversalwrapper>`_ and
diff --git a/repoze/bfg/tests/test_router.py b/repoze/bfg/tests/test_router.py
index 13a5bd11a..6c0497653 100644
--- a/repoze/bfg/tests/test_router.py
+++ b/repoze/bfg/tests/test_router.py
@@ -28,10 +28,9 @@ class TestRouter(unittest.TestCase):
         settings.update(kw)
         self.registry.registerUtility(settings, ISettings)
 
-    def _registerTraverserFactory(self, context, view_name='', subpath=None,
+    def _makeTraverserFactory(self, context, view_name='', subpath=None,
                                   traversed=None, virtual_root=None,
                                   virtual_root_path=None, **kw):
-        from repoze.bfg.interfaces import ITraverser
 
         if virtual_root is None:
             virtual_root = context
@@ -42,8 +41,13 @@ class TestRouter(unittest.TestCase):
         if virtual_root_path is None:
             virtual_root_path = []
 
+        from zope.interface import implements
+        from repoze.bfg.interfaces import ITraverser
+
         class DummyTraverserFactory:
-            def __init__(self, root):
+            implements(ITraverser)
+
+            def __init__(self, root=None):
                 self.root = root
 
             def __call__(self, path):
@@ -57,6 +61,11 @@ class TestRouter(unittest.TestCase):
                 kw.update(values)
                 return kw
 
+        return DummyTraverserFactory
+
+    def _registerTraverserFactory(self, *args, **kwargs):
+        DummyTraverserFactory = self._makeTraverserFactory(*args, **kwargs)
+        from repoze.bfg.interfaces import ITraverser
         self.registry.registerAdapter(DummyTraverserFactory, (None,),
                                       ITraverser, name='')
 
@@ -147,6 +156,31 @@ class TestRouter(unittest.TestCase):
         self.failIf('debug_notfound' in result[0])
         self.assertEqual(len(logger.messages), 0)
 
+    def test_call_traverser_model(self):
+        environ = self._makeEnviron()
+        from zope.interface import Interface
+        class IContext(Interface):
+            pass
+        context = DummyContext()
+        from zope.interface import directlyProvides
+        directlyProvides(context, IContext)
+        RootFactory = self._makeTraverserFactory(context, view_name='def')
+        root = RootFactory()
+        self._registerRootFactory(root)
+        from repoze.bfg.interfaces import IRequest
+        response = DummyResponse()
+        response.app_iter = ['Hello world']
+        view = DummyView(response)
+        self._registerView(view, 'def', IContext, IRequest)
+        logger = self._registerLogger()
+        router = self._makeOne()
+        start_response = DummyStartResponse()
+        result = router(environ, start_response)
+        self.assertEqual(result, ['Hello world'])
+        headers = start_response.headers
+        status = start_response.status
+        self.assertEqual(status, '200 OK')
+
     def test_has_webob_adhoc_attrs(self):
         environ = self._makeEnviron()
         environ['webob.adhoc_attrs'] = {}
diff --git a/repoze/bfg/traversal.py b/repoze/bfg/traversal.py
index 11e5ca806..580225566 100644
--- a/repoze/bfg/traversal.py
+++ b/repoze/bfg/traversal.py
@@ -273,9 +273,12 @@ def traverse(model, path):
     return _traverse(model, {'PATH_INFO':path})
 
 def _traverse(model, environ):
-    traverser = queryAdapter(model, ITraverser)
-    if traverser is None:
-        traverser = ModelGraphTraverser(model)
+    if ITraverser.providedBy(model):
+        traverser = model
+    else:
+        traverser = queryAdapter(model, ITraverser)
+        if traverser is None:
+            traverser = ModelGraphTraverser(model)
 
     result = traverser(environ)
     return result