// Validates that the value is an integer and is greater than 10
$validator = new ScalarValidator(array(
    'type' => 'integer',
    'gt' => 10
));
$errors = $validator->validate(9);
foreach ($errors as $error) {
    echo $error;
    echo "\r\n";
}

// Validates that a value is an array and keys must fit these requirements:
// key1 and key2 are required
// key3 is optional
// key4 is denied
$validator = new ArrayValidator(array(
    'requiredKeys' => array('key1', 'key2'),
    'allowedKeys' => array('key3'),
    'deniedKeys' => array('key4')
));
$errors = $validator->validate(array('key1' => 'foo1'));

$user = new User();
$user->name = 'John';
$user->age = 30;

// Validates that the property 'name' is a string
// and the property 'age' is an integer and is greater than 0
$validator = new ObjectValidator(array(
    'name' => new ScalarValidator(array(
        'type' => 'string'
    )),
    'age' => new ScalarValidator(array(
        'type' => 'integer'
        'gt' => 0
    ))
));
$errors = $validator->validate($user);