[Zope3-checkins] SVN: Zope3/trunk/src/zope/ fire events before updating viewlets in manager

[Bernd Dorn]

Log message for revision 74234:
  fire events before updating viewlets in manager

Changed:
  U   Zope3/trunk/src/zope/contentprovider/interfaces.py
  U   Zope3/trunk/src/zope/viewlet/README.txt
  U   Zope3/trunk/src/zope/viewlet/manager.py

-=-
Modified: Zope3/trunk/src/zope/contentprovider/interfaces.py
===================================================================
--- Zope3/trunk/src/zope/contentprovider/interfaces.py	2007-04-18 05:34:45 UTC (rev 74233)
+++ Zope3/trunk/src/zope/contentprovider/interfaces.py	2007-04-18 09:24:06 UTC (rev 74234)
@@ -21,6 +21,7 @@
 import zope.interface
 from zope.tales import interfaces
 from zope.publisher.interfaces import browser
+from zope.component.interfaces import ObjectEvent, IObjectEvent
 
 class IUpdateNotCalled(zope.interface.common.interfaces.IRuntimeError):
     """Update Not Called
@@ -35,6 +36,16 @@
 # Make it a singelton
 UpdateNotCalled = UpdateNotCalled('``update()`` was not called yet.')
 
+class IBeforeUpdateEvent(IObjectEvent):
+
+    """A Contentprovider will be updated"""
+    
+class BeforeUpdateEvent(ObjectEvent):
+
+    """A Contentprovider willt be updated"""
+
+    zope.interface.implements(IBeforeUpdateEvent)
+
 class IContentProvider(browser.IBrowserView):
     """A piece of content to be shown on a page.
 
@@ -99,7 +110,6 @@
         raise an ``UpdateNotCalled`` error.
         """
 
-
 class IContentProviderType(zope.interface.interfaces.IInterface):
     """Type interface for content provider types (interfaces derived from
        IContentProvider).

Modified: Zope3/trunk/src/zope/viewlet/README.txt
===================================================================
--- Zope3/trunk/src/zope/viewlet/README.txt	2007-04-18 05:34:45 UTC (rev 74233)
+++ Zope3/trunk/src/zope/viewlet/README.txt	2007-04-18 09:24:06 UTC (rev 74234)
@@ -121,9 +121,20 @@
   ...      IBrowserView, ILeftColumn),
   ...     interfaces.IViewlet, name='sport')
 
-and thus the left column is filled:
+and thus the left column is filled. Note that also events get fired
+before viewlets are updated. We register a simple handler to
+demonstrate this behaviour.
 
+  >>> from zope.contentprovider.interfaces import IBeforeUpdateEvent
+  >>> events = []
+  >>> def handler(ev):
+  ...     events.append(ev)
+  >>> zope.component.provideHandler(handler, (IBeforeUpdateEvent,))
   >>> leftColumn.update()
+  >>> [(ev, ev.object.__class__.__name__) for ev in events]
+  [(<zope.contentprovider.interfaces.BeforeUpdateEvent...>, 'SportBox'),
+   (<zope.contentprovider.interfaces.BeforeUpdateEvent...>, 'WeatherBox')]
+  
   >>> print leftColumn.render()
   <div class="box">Patriots (23) : Steelers (7)</div>
   <div class="box">It is sunny today!</div>

Modified: Zope3/trunk/src/zope/viewlet/manager.py
===================================================================
--- Zope3/trunk/src/zope/viewlet/manager.py	2007-04-18 05:34:45 UTC (rev 74233)
+++ Zope3/trunk/src/zope/viewlet/manager.py	2007-04-18 09:24:06 UTC (rev 74234)
@@ -20,10 +20,12 @@
 import zope.component
 import zope.interface
 import zope.security
+import zope.event
 from zope.app.pagetemplate.viewpagetemplatefile import ViewPageTemplateFile
 
 from zope.viewlet import interfaces
 from zope.location.interfaces import ILocation
+from zope.contentprovider.interfaces import BeforeUpdateEvent
 
 class ViewletManagerBase(object):
     """The Viewlet Manager Base
@@ -107,8 +109,10 @@
         self._updateViewlets()
 
     def _updateViewlets(self):
-        # Update all viewlets
-        [viewlet.update() for viewlet in self.viewlets]
+        """Calls update on all viewlets and fires events"""
+        for viewlet in self.viewlets:
+            zope.event.notify(BeforeUpdateEvent(viewlet))
+            viewlet.update()
 
     def render(self):
         """See zope.contentprovider.interfaces.IContentProvider"""