<?php

abstract class VigiloXml

{

    abstract public function __toString();

    public static function sprintf($s)

    {

        $args = func_get_args();

        array_shift($args); // pop $s

        $new_args = array();

        foreach ($args as $arg) {

            if (is_string($arg)) {

                $new_args[] = htmlspecialchars($arg, ENT_XML1 | ENT_QUOTES, "utf-8");

            } elseif (is_array($arg)) {

                $acc = '';

                foreach ($arg as $sub) {

                    if (is_object($sub)) {

                        $acc .= (string) $sub;

                    }

                }

                $new_args[] = $acc;

            } else {

                $new_args[] = (string) $arg;

            }

        }

        return vsprintf($s, $new_args);

    }

}