public function classFileExists($classFile)
    {
        if (file_exists($classFile)) {
            return true;
        }
        foreach (explode(PATH_SEPARATOR, get_include_path()) as $path) {
            if (file_exists($path) && file_exists($path.DIRECTORY_SEPARATOR.$classFile)) {
                return true;
            }
        }
        return false;
    }