Methods in {{Zend_Cache_Backend_File}} are either {{public}} or {{private}}. Using {{protected}} instead of {{private}} would allow ZF users to augment {{Zend_Cache_Backend_File}} without modifying the original code.

Behold the horror we had to do :

if (!class_exists('Zend_Cache_Backend_File_X')) {
    $path = 'Zend/Cache/Backend/File.php';
    $data = file_get_contents($path);
    $data = str_replace('Zend_Cache_Backend_File', 'Zend_Cache_Backend_File_X', $data);
    $data  = str_replace('private', 'protected', $data);
    eval(substr($data, 5)); // Remove PHP tag
}

Please save us from ourselves!