gistfile1.php

class Callbacks
{
	protected $_callbacks = array(
		"cb" => function($value) {
			return $value;
		}
	);

	public function call($name, $parameters)
	{
		if (isset($_callbacks[$name]))
		{
			return call_user_func_array($this->_callbacks[$name], $parameters);
		}
	}
}

$new = new Callbacks();
$new->call("cb", array("hello world"));