class FactoryMixIn:

    """Mix-in class to pass a factory object instead of RequestHandlerClass.

    New usage:

    - If needed, extend the __init__ method of the request handler to pass extra parameters.
    - Define a factory object with a method start() that instantiates a RequestHandlerClass.
    - Use None for the RequestHandlerClass parameter when you instantiate the server.
    - Before you handle the request, pass the factory object in set_factory().

    """

    def set_factory(self, requesthandlerfactory):
        """Set a factory instance that will instantiate the RequestHandlerClass."""
        self.requesthandlerfactory = requesthandlerfactory

    def finish_request(self, request, client_address):
        """Finish one request by calling the request handler factory."""
        self.requesthandlerfactory.start(request, client_address, self)