diff -r 022e881b758e -r 3b7a38af5c42 tools.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tools.py	Sun Feb 03 23:39:27 2008 +0100
@@ -0,0 +1,62 @@
+class AbstractRegister(object):
+    _instance = None
+    _registered_type = None
+    def __new__(cls):
+        # implements a singleton
+        if cls._instance is None:
+            #debug('Instanciating %s', cls.__name__)
+            cls._instance = super(AbstractRegister, cls).__new__(cls)
+            cls._instance.registered = {}
+            cls._instance.accepts = set()
+        return cls._instance
+    
+    def add(self, cls):
+        assert issubclass(cls, self._registered_type)
+        if cls is self._registered_type:
+            return
+        if cls._accepts is None:
+            return
+        #assert isinstance(cls._accepts, (basestring, tuple))
+        
+        #debug("Registerered %s for %s", cls.__name__)
+        if not isinstance(cls._accepts, tuple):
+            cls._accepts = (cls._accepts,)
+        for key in cls._accepts:
+            key = self._get_typ(key)
+            #debug("  new key = %s", key)            
+            self.registered.setdefault(key, []).append(cls)
+            self.accepts.add(key)
+
+    def _get_typ(self, typ):
+        if not isinstance(typ, basestring):
+            if not isinstance(typ, type):
+                return None
+            typ = typ.__name__
+        return typ
+    
+    def __contains__(self, val):
+        val = self._get_typ(val)
+        return val in self.accepts
+
+    def get_class(self, typ):
+        item = typ
+        if not isinstance(typ, type):
+            typ = typ.__class__
+        name = typ.__name__
+        #debug("Looking a widget for %s", typ.__name__)
+        orig_typ = typ
+        while typ is not None:
+            if typ.__name__ in self.registered:
+                for w in self.registered[typ.__name__]:
+                    if w._filter is None or w._filter(item):
+                        #debug("Widget for %s is %s", typ.__name__, w)
+                        return  w#self.registered[typ.__name__]
+            if typ.__bases__:
+                typ = typ.__bases__[0]
+                if typ == object:
+                    typ = None
+                elif typ.__name__ in ("ObjectItem_", "AbstractListItem_"):
+                    typ = orig_typ._type
+            else:
+                typ = None
+        raise ValueError('No registered class for %s' % (name))