Python and the XML Document Object Model (DOM) with 4Suite

This method handles the special case where the Element() constructor is called to set up the document's root element.

# - - -   E l e m e n t . _ _ w r a p R o o t   - - -

    def __wrapRoot ( self, parent, **attrs ):
        """Set up an Element wrapping the document root element.

          [ (parent is a Document) and
            (attrs is a dictionary of attribute names and values) ->
              self.node  :=  parent.node.documentElement with
                  attributes from attrs attached
              self.doc   :=  parent ]
        """

Since the actual DOM Element has already been created, and lives in the document's .documentElement attribute, all we have to do is set up the class invariants, then copy in any attributes from the attrs argument.

        #-- 1 --
        self.node  =  parent.node.documentElement
        self.doc   =  parent

        #-- 2 --
        # [ if attrs is a dictionary ->
        #     self.node  :=  self.node with attribute names
        #         (with trailing "_" removed if present) and
        #         corresponding values from attrs
        #   else -> I ]
        if  attrs:
            self.update ( attrs )