Simple PHP shutdown function manager

ShutdownFunctionManager.php

<?php

class ShutdownFunctionManager {
    protected $callbacks = array();
    protected $registered = false;

    public function __construct($auto_register = true) {
        if ($auto_register) {
            $this->register();
        }
    }

    public function append($callback, $parameter = null) {
        $this->callbacks[] = $this->parseArgs(func_get_args());
    }

    public function clear() {
        $this->callbacks = array();
    }

    public function parseArgs($args) {
        return array($args[0], array_slice($args, 1));
    }

    public function prepend($callback, $parameter = null) {
        array_unshift($this->callbacks, $this->parseArgs(func_get_args()));
    }

    public function register() {
        if (!$this->registered) {
            register_shutdown_function(array($this, 'shutdown'));
            $this->registered = true;
        }
    }

    public function shutdown() {
        foreach ($this->callbacks as $callback) {
            call_user_func_array($callback[0], $callback[1]);
        }
    }
}