KFileFinder OOPHP5 (See related posts)

<?php

/**
  * Recursively find a file by its name in a directory.
  *
  * Found files are cached onto the current session for
  * quicker access next time.
  *
  * Requires PHP 5
  *
  * by theredhead
  */
class KFileFinder
{
        public $dir  = null;
        public $file = null;
        
        public function __construct( $file = null, $dir = null )
        {
            // did we give a directory?
                if ( $dir == null )
                {
                    // no, start searching under the servers public root
                        $this->dir = realpath( $_SERVER[ 'DOCUMENT_ROOT' ].'/../' );
                } else {
                        $this->dir = $dir;
                }

        // let the instance know what file to look for
                if ( $file !== null )
                {
                        $this->file = $file;
                }
                
                return $this;
        }
        
        // static method: $result = KFileFinder::findFile( 'guestbook.xml' );
        public static function findFile( $file, $dir = null )
        {
                $finder = new KFileFinder( $file, $dir );
                $result = $finder->find();
                unset($finder);
                return $result;
        }
        
        // instance method: $result = $myFinder->find( 'guestbook.xml' );
        public function find( $dir = null )
        {
            // cache found file into the session so we only have to search
            // for it the first time and when it moved    
            if (isset($_SESSION[ 'KFileFinder' ][ $this->file ]) &&
                file_exists($_SESSION[ 'KFileFinder' ][ $this->file ]))
            {
                return $_SESSION[ 'KFileFinder' ][ $this->file ];
            }
            
                $found = false;

                if ( $dir == null )
                {
                        $d = $this->dir;
                } else {
                        $d = $dir;
                }

                $iterator = new DirectoryIterator( $d );
        // the loop
                while( $iterator->valid() && $found == false )
                {
                        if ( !$iterator->isDot() && $iterator->isDir() )
                        {
                                $pathToCheck = $iterator->getPathname().'/'.$this->file;
                                // test if the file existts and if we can read it
                                if ( file_exists( $pathToCheck ) && is_readable( $pathToCheck ))
                                {
                                        $found = $pathToCheck;
                                } else {
                                        $found = $this->find( $iterator->getPathname() );
                                }
                        }
                        $iterator->next();
                }
                // cache the result
                $_SESSION[ 'KFileFinder' ][ $this->file ] = $found;
                return $found;
        }
}

?>