<?php
class FileHandler {
    private static $_instance = null;
    private function __construct() {
        // restrict access to the constructor
    }
    public static function getInstance() {
     if ( is_null ( self::$_instance ) ) {
     self::$_instance = new self();
     }
     return self::$_instance;
    }
    /**
     * Convenience function for testing.
     * Clears the current instance so that it can be reinstantiated rather
     * than retrieving the existing instance. Helpful when testing new
     * properties, etc.
     */
    public function clear() {
        self::$_instance = null;
    }
    public function save ( $rootPath, $source, $fileName, $isTemporary ) {
        ...
    }
    public function delete ( $file ) {
        ...
    }
    protected function getBinDir() {
        return chr ( ( rand ( 0, 25 ) ) + 97 );
    }
    public function checkFileSize ( $file, $max ) {
        ...
    }
}
?>