[Zope3-checkins] CVS: Zope3/src/zope/app - context.txt:1.7

[Steve Alexander]

Update of /cvs-repository/Zope3/src/zope/app
In directory cvs.zope.org:/tmp/cvs-serv21282/src/zope/app

Modified Files:
	context.txt 
Log Message:
Added note about decorators calling context aware descriptors of proxied
objects, the consequences, and what we should do about it.


=== Zope3/src/zope/app/context.txt 1.6 => 1.7 ===
--- Zope3/src/zope/app/context.txt:1.6	Sat Jun 14 09:11:04 2003
+++ Zope3/src/zope/app/context.txt	Wed Jul  2 16:54:05 2003
@@ -281,3 +281,25 @@
   into context-aware descriptors through deriving new classes.
   Such unpredictability and implicitness is bad.
 
+* Using ContextDescriptors from a decorator
+
+  Context decorators usually have methods that look like this:
+
+    def setObject(self, name, obj):
+        name = getProxiedObject(self).setObject(name, object)
+        # send events
+        # call hooks
+        return name
+
+  A problem with this is that getProxiedObject(self) will usually return
+  an unwrapped object. So, even if setObject on the proxied object is a
+  ContextDescriptor, it will not be called with 'self' rebound to the
+  wrapper instance.
+
+  The way around this is to write a special getProxiedObject that is the
+  moral equivalent to 'super', and does the right thing for context-aware
+  descriptors.
+
+  For now, though, a ContextDescriptor of an object must not be called from
+  its decorator.
+