Remove module-level factory methods in favor of having a factory class-method

on wsgi components themselves.  Local options from config are passed to the
__init__ method of the component as kwargs.

nova/wsgi.py

@@ -67,15 +67,28 @@ class Application(object):
 
     @classmethod
     def factory(cls, global_config, **local_config):
-        """Used for paste app factories in paste.deploy config fles."""
+        """Used for paste app factories in paste.deploy config fles.
-        rv = cls()
+
-        for k,v in local_config.iteritems():
+        Any local configuration (that is, values under the [app:APPNAME]
-            if hasattr(rv, k):
+        section of the paste config) will be passed into the `__init__` method
-                setattr(rv, k, v)
+        as kwargs.
-            else:
+
-                logging.debug(_("Unknown local config option %s for %s"),
+        A hypothetical configuration would look like:
-                              k, cls)
+
-        return rv
+            [app:wadl]
+            latest_version = 1.3
+            paste.app_factory = nova.api.fancy_api:Wadl.factory
+
+        which would result in a call to the `Wadl` class as
+
+            import nova.api.fancy_api
+            fancy_api.Wadl(latest_version='1.3')
+
+        You could of course re-implement the `factory` method in subclasses,
+        but using the kwarg passing it shouldn't be necessary.
+
+        """
+        return cls(**local_config)
 
     def __call__(self, environ, start_response):
         r"""Subclasses will probably want to implement __call__ like this:
@@ -123,16 +136,29 @@ class Middleware(Application):
 
     @classmethod
     def factory(cls, global_config, **local_config):
-        """Used for paste app factories in paste.deploy config fles."""
+        """Used for paste app factories in paste.deploy config fles.
+
+        Any local configuration (that is, values under the [filter:APPNAME]
+        section of the paste config) will be passed into the `__init__` method
+        as kwargs.
+
+        A hypothetical configuration would look like:
+
+            [filter:analytics]
+            redis_host = 127.0.0.1
+            paste.filter_factory = nova.api.analytics:Analytics.factory
+
+        which would result in a call to the `Analytics` class as
+
+            import nova.api.analytics
+            analytics.Analytics(app_from_paste, redis_host='127.0.0.1')
+
+        You could of course re-implement the `factory` method in subclasses,
+        but using the kwarg passing it shouldn't be necessary.
+
+        """
         def _factory(app):
-            rv = cls(app)
+            return cls(app, **local_config)
-            for k,v in local_config.iteritems():
-                if hasattr(rv, k):
-                    setattr(rv, k, v)
-                else:
-                    logging.debug(_("Unknown local config option %s for %s"),
-                                  k, cls)
-            return rv
         return _factory
 
     def __init__(self, application):  # pylint: disable-msg=W0231