convert text into typecode specific data.

def text_to_data(self, text, elt, ps):
        '''convert text into typecode specific data.
        '''
        if self.pyclass is not None:
            v = self.pyclass(text) 
        else:
            try:
                v = int(text)
            except:
                try:
                    v = long(text)
                except:
                    raise EvaluateException('Unparseable integer', 
                        ps.Backtrace(elt))
        return v