WIP

echo/containers.py

@@ -7,7 +7,12 @@
 
 class ContainerMixin:
 
+    def _setup_container(self):
+        self.
+
     def _prepare_add(self, value):
+        for validator in self._item_validators:
+            value = validator(value)
         if isinstance(value, list):
             value = CallbackList(self.notify_all, value)
         elif isinstance(value, dict):
@@ -24,6 +29,11 @@ def _cleanup_remove(self, value):
         elif isinstance(value, (CallbackList, CallbackDict)):
             value.callbacks.remove(self.notify_all)
 
+    def add_item_validator(self, validator, priority=0):
+        self._item_validators.append(validator, priority=priority)
+
+    # TODO: implement remove_item_validator
+
 
 class CallbackList(list, ContainerMixin):
     """
@@ -37,6 +47,7 @@ def __init__(self, callback, *args, **kwargs):
         super(CallbackList, self).__init__(*args, **kwargs)
         self.callbacks = CallbackContainer()
         self.callbacks.append(callback)
+        self._item_validators = CallbackContainer()
         for index, value in enumerate(self):
             super().__setitem__(index, self._prepare_add(value))
 
@@ -115,6 +126,7 @@ def __init__(self, callback, *args, **kwargs):
         super(CallbackDict, self).__init__(*args, **kwargs)
         self.callbacks = CallbackContainer()
         self.callbacks.append(callback)
+        self._item_validators = CallbackContainer()
         for key, value in self.items():
             super().__setitem__(key, self._prepare_add(value))