ImmutableValueObjectExample.php

<?php

error_reporting(E_STRICT | E_ALL);

class ImmutableValueObject extends \ArrayObject
{
    public function __construct(array $data = array(), $flags = \ArrayObject::ARRAY_AS_PROPS)
    {
        parent::__construct($data, $flags);
    }
    
    public function offsetSet($name, $value)
    {
        throw new \RuntimeException('This object is immutable');
    }
    
    public function offsetUnset($name)
    {
        throw new \RuntimeException('This object is immutable');
    }
}

$f = new ImmutableValueObject(array('foo' => 'bar', 'baz' => 'bum'));


echo $f['foo'] . PHP_EOL;
echo $f->baz . PHP_EOL;

try {
    $f['baz'] = 'bee';
} catch (\Exception $e) {
    echo 'Exception thrown as expected' . PHP_EOL;
}

try {
    $f->baz = 'bee';
} catch (\Exception $e) {
    echo 'Exception thrown as expected' . PHP_EOL;
}

try {
    $f->append('bee');
} catch (\Exception $e) {
    echo 'Exception thrown as expected' . PHP_EOL;
}

try {
    unset($f['baz']);
} catch (\Exception $e) {
    echo 'Exception thrown as expected' . PHP_EOL;
}