add method to FilenameArray via hook does not work

[bernhard]

hi!

i try to add a custom method to FilenameArray class to check if a file exists and remove it from array if not...

    public function init() {
        $this->addHook('FilenameArray::cleanup', $this, 'cleanupFileArray');
    }

    /**
     * remove non existant files from file array
     */
    public function cleanupFileArray($event) {
        // do some stuff
    }

but i always get the error

Fatal Error
Call to undefined method ProcessWire\FilenameArray::cleanup()

it works when i use Page::cleanup and Pages::cleanup and also when i add the method directly into the core file... but thats no option. what am i doing wrong?

[Soma]

FilenameArray is just a helper class not a Wire class like Page or Pages.