Why must the cache directory be writeable?

The standard PHP-Nuke block RSS reader caches feeds in the nuke_blocks table, along with the definition of the feed.  nukePIE uses SimplePie, which caches feeds in files in the cache directory.  To do this, the cache directory must be writeable - but it is protected from abuse in a number of ways, including the htaccess file included in the cache directory.

SimplePie automatically refreshes the cache file in the cache directory, but if you delete an RSS block, the unused cache file will remain in the cache directory. You can delete all the cache files (but not .htaccess and index.html) in the cache directory at any time, and any used by active blocks will be restored the next time the block is displayed.

This Q&A was found on: https://nukeseo.com/modules.php?name=FAQ&file=index&myfaq=yes&id_cat=4