import logging

old_factory = logging.getLogRecordFactory()

def record_factory(*args, **kwargs):
    record = old_factory(*args, **kwargs)
    record.test = kwargs['value'] ** kwargs['power']
    return record

logging.setLogRecordFactory(record_factory)

FORMAT = '%(asctime)-15s %(test)d  %(message)s'
logging.basicConfig(format=FORMAT)

logging.warning("test", value=2, power=4)