def _get_callback(self):
        if self._callback is not None:
            return self._callback
        try:
            self._callback = get_callable(self._callback_str)
        except ImportError, e:
            mod_name, _ = get_mod_func(self._callback_str)
            raise ViewDoesNotExist, "Could not import %s. Error was: %s" % (mod_name, str(e))
        except __HOLE__, e:
            mod_name, func_name = get_mod_func(self._callback_str)
            raise ViewDoesNotExist, "Tried %s in module %s. Error was: %s" % (func_name, mod_name, str(e))
        return self._callback
dataset/ETHPy150Open dcramer/django-compositepks/django/core/urlresolvers.py/RegexURLPattern._get_callback