[XML-SIG] XPath and Zope's ParsedXML DOM

[Jeremy Kloth]

From: "Martijn Faassen" <faassen@vet.uu.nl>
> Hi there,
>
> I've been trying to make XPath work with Zope's DOM implementation,
> ParsedXML. In the process I've discovered some incompatibilities in
> XPath that I had to hack around.
>
> The problem is as follows. ParsedXML uses DOM nodes that are
> descendants of ExtensionClass. This means that type(node) !=
types.InstanceType.
>

Instead of doing the check every time, I implemented a more lazy approach to
it.  Additionally, the performance hit happens only the first time through.

def _strUnknown(object):
    # Allow for non-instance DOM node objects
    if hasattr(object, 'nodeType'):
        # Add this type to the mapping for next time through
        _strConversions[type(object)] = _strInstance
        return _strInstance(object)
    return

and change type types.ListType entry in _strConversions to:

    types.ListType : lambda x: x and _strConversions.get(type(x[0]),
_strUnknown)(x[0]) or '',

--
Jeremy Kloth                              Consultant
jeremy.kloth@fourthought.com              +1 303 583 9900 x 105
Fourthought, Inc.                         http://fourthought.com
4735 East Walnut St, Boulder, CO  80301, USA
XML strategy, XML tools (http://4suite.org), knowledge management