[Zope] Accessing self in External Methods

Hi, I am using an external method to call wvWare and catalog a M$-Word file content. The file object is an attribute of my ZClass. The external method is called by a Python Script (PrincipiaSearchSource). I´d like to know how can I access the file atribute from the external method. I tryed directly: self.file, but it didn´t work. Does that mean ZClasses atributes are always private? How can I get this file object? Using getattr? One more question: how can I modify a class attribute inside the External Method? thanks, Rogerio