View.php
public static function versionControl($file)
    {
        if (!\defined('SERVER_ROOT')) {
            return DS . $file;
        }
        try {
            if (!file_exists($absolute = APP_ROOT . $file) || !($time = @filemtime($absolute))) {
                return DS . $file;
            }
            return preg_replace('{\\.([^./]+)$}', '.' . $time . '.\$1', DS . $file);
        } catch (\ErrorException $e) {
            return DS . $file;
        }
    }
public static function versionControl($file)
    {
        if (!\defined('SERVER_ROOT')) {
            return DS . $file;
        }
        try {
            if (!file_exists($absolute = APP_ROOT . $file) || !($time = @filemtime($absolute))) {
                return DS . $file;
            }
            return preg_replace('{\\.([^./]+)$}', '.' . $time . '.\$1', DS . $file);
        } catch (\ErrorException $e) {
            return DS . $file;
        }
    }
Given a file, i.e. /css/base.css, replaces it with a string containing the
file's mtime, i.e. /css/base.1221534296.css.

@param $file
file to be loaded.  Must be an absolute path (i.e.
starting with slash).
@return mixed  file to be loaded.