Reflection capability in IcePy?

Is there a way to determine the types of a python slice field at run-time? Internally, Ice knows what the field should be and can display that information:

    _name = <invalid value - expected ::omero::RString>

Here, an RString is a subclass of a generic RType. In our django-based web app dynamically determining which subclass to use field fails when that field is None.

Any ideas, guys?
Thanks!