added some experimental stuff for self-registering adapters using a metaclass

git-svn-id: svn://svn.cy55.de/Zope3/src/cybertools/trunk@2465 fd906abe-77d9-0310-91a1-e0d9ade77398

util/adapter.py

@@ -56,3 +56,29 @@ class AdapterFactory(object):
         if adapter is None:
             return None
         return adapter(obj)
+
+
+# self-registering adapters
+
+adapters = AdapterFactory()
+
+
+class AdapterType(type):
+    """ To be used as metaclass for self-registering adapters.
+    """
+
+    def __init__(cls, name, bases, cdict):
+        super(AdapterType, cls).__init__(name, bases, cdict)
+        info = list(cdict.get('__adapterinfo__', (adapters, object, '')))
+        if len(info) < 2:
+            info.append(object)
+        if len(info) < 3:
+            info.append('')
+        factory, adapted, name = info
+        factory.register(cls, adapted, name)
+
+
+class AdapterBase:
+
+    __metaclass__ = AdapterType
+

util/adapter.txt

@@ -7,6 +7,10 @@ $Id$
 To work with adapters we need at least two classes, one for objects
 that we want to adapt to (the adapter's `context`) and one for the adapters.
 
+
+Adapter Classes and Factories
+=============================
+
   >>> class Content(object):
   ...     pass
 
@@ -100,3 +104,22 @@ example above.
   >>> c2
   <Content object ...>
 
+
+Self-registering Adapters
+=========================
+
+  >>> from cybertools.util.adapter import adapters, AdapterBase
+  >>> stateful = AdapterFactory()
+
+  >>> class StateAdapter(AdapterBase):
+  ...     __adapterinfo__ = stateful, Content
+  ...     def __init__(self, context):
+  ...         self.context = context
+  ...     def setState(self, state):
+  ...         self.context._state = state
+  ...     def getState(self):
+  ...         return getattr(self.context, '_state', 'initial')
+
+  >>> stateful._registry
+  {(<class 'Content'>, ''): <class 'StateAdapter'>}
+