History for Top Level Document

??changed:
-
Issue:

Is there a need for a top level Document for all objects to reference as thier ownerDocument?

Notes:

 Mike -- Further investigation shows a class called Root defined in  ZDOM.py.  This class is a base class for the Application.

  Jim -- Which is wrong, as Amos has pointed out to us
    several times. Sigh.

    Of course, this doen't really have anything to do with
    *whether* there should be a top-level document.

 Mike -- Having a Document as the "Parent" class will not work well in  Zope.  A document is only allowed one element child, the document  element.  what we really neeed to say is that the application is trhe  document element.

   Jim -- Right.

Resolution:

  Jim -- You need to tell us whether Zope needs to have a 
    top-level Document.
  
    If the answer is yes, then it should be provided as a
    sub-object defined in (a base class of) the Aplication 
    class. Something like:

    In ZDOM.py or some such::

       class ZopeDocument(Acquisition.Implicit, ...):
          """Implement the document interface

          For the document that is Zope. :)
          """

          # Note that we get at our top-level element
          # and the rest of the object system though
          # aq_parent, which we get because we acquire.

          ...

       class ZopeTopLevelElement(...):

          OwnerDocument=ZopeDocument()

          ....

    In Application.py::

       class Application(..., ZDOM.ZopeTopLevelElement, ...):
          ...
          

Mike -- This is the way I have implemented it.  A super class of element called RootElement is a base class for application.  The root element needs to be a special case, not for owner document support, but because it is the acuisition parent of all other nodes hence its parentNode attribute functions differently.  I create a singleton Document for the Application when it is first created.

  Jim -- The singleton should be defined in the class.

    There's no reason to store it in the application
    object.

   Mike -- It is not.  It is defined in RootElement.py as a singleton.