parameter_status (PGconn)

    /*
     * call-seq:
     *    conn.parameter_status( param_name ) -> String
     *
     * Returns the setting of parameter _param_name_, where
     * _param_name_ is one of
     * * +server_version+
     * * +server_encoding+
     * * +client_encoding+
     * * +is_superuser+
     * * +session_authorization+
     * * +DateStyle+
     * * +TimeZone+
     * * +integer_datetimes+
     * * +standard_conforming_strings+
     *
     * Returns nil if the value of the parameter is not known.
     */
    static VALUE
    pgconn_parameter_status(VALUE self, VALUE param_name)
    {
            const char *ret = PQparameterStatus(get_pgconn(self),
                            StringValuePtr(param_name));
            if(ret == NULL)
                    return Qnil;
            else
                    return rb_tainted_str_new2(ret);
    }