# Abstract class serving as an interface for concrete sites. class ActiveFile::Site def initialize end def upload(key, data) raise NotImplementedError end def download(key) raise NotImplementedError end def delete(key) raise NotImplementedError end def exists?(key) raise NotImplementedError end def url(key) raise NotImplementedError end def checksum(key) raise NotImplementedError end def copy(from_key:, to_key:) raise NotImplementedError end def move(from_key:, to_key:) raise NotImplementedError end end module ActiveFile::Sites end