def get_param_names(p_space):
    """Return list of parameter names.

    Parameters
    ----------
    p_space : class
        A class containing attributes exclusively of `PaddyParameter`
        instances.

    Returns
    -------
    param_name_list : list of strings
        A list of `PaddyParameter` instances as string types of the instance
        variable name.

    """
    param_name_list = []
    for i in vars(p_space):
        param_name_list.append(i)
    return param_name_list