PHP4 - PHP5 : Compatibilité ?

function commonsetup() {
  @session_start();
  $interface = & new interface($globals['interfaces'][0]['maquette']);

$globals['clsinterface'] = null;

   function getmicrotime() {
	list($usec, $sec) = explode(" ",microtime());
    	return ($usec+$sec);
   } 

class clsinterface { 
   var $maquette;
   var $variables = array();
   var $start;
   // menu locator
   var $locator;
   // boutton
   var $maquettebtn;

   function clsinterface ($file) {
	if (!file_exists($file)) {
        	die('un problème d\'ordre majeur s\'est produit');
	}
 	$this->locator = array();
   	$this->locator['niveau'] = 0;

   	// création de la function de flush :
   	$flushsite = create_function('$str','	
		$this = & $globals["clsinterface"];
		$this->variables["[body]"] = $str;
		$this->variables["[exectime]"] = round(getmicrotime()-($this->start),4);
		$this->variables["[locator]"] = $this->locator["start"].$this->locator["string"];
		return str_replace(array_keys($this->variables),
				array_values($this->variables),$this->maquette);
   			');
	$this->start = getmicrotime();

	// chargement de la maquette 
	$this->maquette = file_get_contents($file);
	$globals['clsinterface'] = & $this;
	ob_start($flushsite);
   }

<?php

class clsinterface {
  private static $instance;

  public static function getinstance($file = NULL) {
    if (null === $file && null === self::$instance) {
      throw new Exception('File is required to create a new instance');
    }
    null === self::$instance or self::$instance = new self($file);
    return self::$instance;
  }

  private function __construct($file) {
    if (!file_exists($file)) {
      throw new Exception("Le fichier $file n'existe pas");
    }
  }
}?>

  public function flush($str) {
    $this->variables["[body]"] = $str;
    $this->variables["[exectime]"] = round(getmicrotime()-($this->start),4);
    $this->variables["[locator]"] = $this->locator["start"].$this->locator["string"];
    return str_replace(array_keys($this->variables), array_values($this->variables),$this->maquette);

  private function __construct($file) {
    if (!file_exists($file)) {
      throw new Exception("Le fichier $file n'existe pas");
    }
    ob_start(array($this, 'flush'));
  }

$interface = clsinterface::getinstance('/path/to/my/file.ext');