src/pyams_utils/container.py
changeset 195 65b6d930b42b
parent 72 9049384a2bd4
child 225 8d7721d95b68
--- a/src/pyams_utils/container.py	Thu Jun 14 08:58:27 2018 +0200
+++ b/src/pyams_utils/container.py	Thu Jun 14 13:57:57 2018 +0200
@@ -17,6 +17,7 @@
 
 # import interfaces
 from zope.container.interfaces import IContainer, IContained
+from zope.lifecycleevent.interfaces import IObjectMovedEvent
 from zope.location.interfaces import ISublocations
 
 # import packages
@@ -38,6 +39,44 @@
         self._order = PersistentList()
 
 
+class ParentSelector(object):
+    """Interface based parent selector
+
+    This selector can be used as a subscriber predicate on IObjectAddedEvent to define
+    an interface that the new parent must support for the event to be applied::
+
+    .. code-block:: python
+
+        from pyams_utils.interfaces.site import ISiteRoot
+
+        @subscriber(IObjectAddedEvent, parent_selector=ISiteRoot)
+        def siteroot_object_added_event_handler(event):
+            '''This is an event handler for an ISiteRoot object added event'''
+    """
+
+    def __init__(self, ifaces, config):
+        if not isinstance(ifaces, (list, tuple, set)):
+            ifaces = (ifaces,)
+        self.interfaces = ifaces
+
+    def text(self):
+        return 'parent_selector = %s' % str(self.interfaces)
+
+    phash = text
+
+    def __call__(self, event):
+        if not IObjectMovedEvent.providedBy(event):
+            return False
+        for intf in self.interfaces:
+            try:
+                if intf.providedBy(event.newParent):
+                    return True
+            except (AttributeError, TypeError):
+                if isinstance(event.newParent, intf):
+                    return True
+        return False
+
+
 @adapter_config(context=IContained, provides=ISublocations)
 class ContainerSublocationsAdapter(ContextAdapter):
     """Contained object sub-locations adapter