toggle_$field()

Works for boolean fields, sets the value of the variable to the opposite of what it currently is.

Example:

example.php

<?php
include("lib.php");
load("person");

$p = new person($_GET["person_id"]);
echo $p->active; // outputs "TRUE"
$p->toggle_active();
echo $p->active; // outputs "FALSE"
$p->update();
?>