_detectId example

    public function load($id, $doNotTestCacheValidity = false)
    {
        if (($id = (string)$id) === '') {
            $id = $this->_detectId();
        } else {
            $id = $this->_decodeId($id);
        }
        if (!$this->_verifyPath($id)) {
            Zend_Cache::throwException('Invalid cache id: does not match expected public_dir path');
        }
        if ($doNotTestCacheValidity) {
            $this->_log("Zend_Cache_Backend_Static::load() : \$doNotTestCacheValidity=true is unsupported by the Static backend");
        }

        $fileName = basename($id);