… stored outside of the public directory
…hen empty. This is because on production apps, it's very common for the attachment_path to be a symlink to a shared dir (like public/files => shared/public/files), but attachment_fu was removing the link whenever it was deleting the last attachment file, or even updating it. So the symlink was being deleted and new attachments where being saved directly in a newly created (by attachment_fu) public/files directory in the release path instead of the shared path.
…r thumbnail classes so things work in dev and prod mode
… needed if you want to subclass the attachment class
…oading of the thumbnail class