Support for `__before__` and `__after__` method calls for controllers

For convenience, a `Controller` class now exists from which all classes wanting to implement these methods should descend. This will allow sane cooperative multiple inheritance.

src/milla/app.py

@@ -7,10 +7,12 @@ Please give me a docstring!
 :Updated: $Date$
 :Updater: $Author$
 '''
-import milla.dispatch.traversal
 from webob.exc import HTTPNotFound, WSGIHTTPException
+import milla.dispatch
 import webob
 
+__all__ = ['Application']
+
 class Application(object):
     '''Represents a Milla web application
     
@@ -22,33 +24,81 @@ class Application(object):
        automatically created if a root is given
     :param dispatcher: An object implementing the dispatcher protocol 
     
-    ``Application`` instances are WSGI applications
+    ``Application`` instances are WSGI applications.
+    
+    .. py:attribute:: config
+    
+       A mapping of configuration settings. For each request, the
+       configuration is copied and assigned to ``request.config``.
     '''
 
-    def __init__(self, root=None, dispatcher=None):
+    def __init__(self, dispatcher):
-        if not dispatcher:
+        self.dispatcher = dispatcher
-            if root:
+        self.config = {}
-                self.dispatcher = milla.dispatch.traversal.Traverser(root)
-            else:
-                raise ValueError('Must specify either a root object or a '
-                                 'dispatcher')
-        else:
-            self.dispatcher = dispatcher
 
     def __call__(self, environ, start_response):
+        path_info = environ['PATH_INFO']
         try:
-            func = self.dispatcher.resolve(environ['PATH_INFO'])
+            func = self.dispatcher.resolve(path_info)
         except milla.dispatch.UnresolvedPath:
             return HTTPNotFound()(environ, start_response)
 
         request = webob.Request(environ)
+        request.config = self.config.copy()
+
+        start_response_wrapper = StartResponseWrapper(start_response)
+        request.start_response = start_response_wrapper        
         try:
+            # If the callable has an __before__ attribute, call it
+            if hasattr(func, '__before__'):
+                func.__before__(request)
+            # If the callable is an instance method and its class has
+            # a __before__ method, call that
+            elif hasattr(func, 'im_self') and \
+                hasattr(func.im_self, '__before__'):
+                func.im_self.__before__(request)
+            # The callable might be a partial, so check the inner func
+            elif hasattr(func, 'func'):
+                if hasattr(func.func, '__before__'):
+                    func.func.__before__(request)
+                elif hasattr(func.func, 'im_self') and \
+                    hasattr(func.func.im_self, '__before__'):
+                    func.func.im_self.__before__(request)
             response = func(request)
         except WSGIHTTPException as e:
             return e(environ, start_response)
+        finally:
+            # If the callable has an __after__ method, call it
+            if hasattr(func, '__after__'):
+                func.__after__(request)
+            # If the callable is an instance method and its class has
+            # an __after__ method, call that
+            elif hasattr(func, 'im_self') and \
+                hasattr(func.im_self, '__after__'):
+                func.im_self.__after__(request)
+            # The callable might be a partial, so check the inner func
+            elif hasattr(func, 'func'):
+                if hasattr(func.func, '__after__'):
+                    func.func.__after__(request)
+                elif hasattr(func.func, 'im_self') and \
+                    hasattr(func.func.im_self, '__after__'):
+                    func.func.im_self.__after__(request)
 
-        if isinstance(response, basestring):
+        # The callable might have returned just a string, which is OK,
+        # but we need to wrap it in a WebOb response
+        if isinstance(response, basestring) or not response:
             response = webob.Response(response)
 
-        start_response(response.status, response.headerlist)
+        if not start_response_wrapper.called:
+            start_response(response.status, response.headerlist)
         return response.app_iter
+
+class StartResponseWrapper():
+    
+    def __init__(self, start_response):
+        self.start_response = start_response
+        self.called = False
+    
+    def __call__(self, *args, **kwargs):
+        self.called = True
+        return self.start_response(*args, **kwargs)

src/milla/controllers.py

@@ -0,0 +1,23 @@
+'''Stub controller classes
+
+These classes can be used as base classes for controllers. While any
+callable can technically be a controller, using a class that inherits
+from one or more of these classes can make things significantly easier.
+
+:Created: Mar 27, 2011
+:Author: dustin
+:Updated: $Date$
+:Updater: $Author$
+'''
+class Controller(object):
+    '''The base controller class
+    
+    This class simply provides empty ``__before__`` and ``__after__``
+    methods to facilitate cooperative multiple inheritance.
+    '''
+
+    def __before__(self, request):
+        pass
+
+    def __after__(self, request):
+        pass