#### Structural

def _ignore(items, node):

    '''Used to "comment out" an XML subtree'''

    return None

funcs['_ignore'] = _ignore

structural_funcs.add('_ignore')

def _ref(items, node):

    '''Used to retrieve a value from another XML node

    @param items

        addr=<path> XPath to value, relative to the XML func's parent node

    '''

    items = dict(items)

    try: addr = items['addr']

    except KeyError, e: raise SyntaxError(e)

    target = xpath.get_1(node.parentNode, addr)

    if target != None: value = xml_dom.value(target)

    else: 

        warnings.warn(UserWarning('_ref: XPath reference target missing: '

            +str(addr)))

        value = None

    return value

funcs['_ref'] = _ref

structural_funcs.add('_ref')