`Convert::yEnc`

Convert::yEnc decodes yEncoded files and writes them to disk. File parts are saved to a temporary directory; when all parts of a file have been received, the completed file is moved to its final location.

Convert::yEnc maintains a database of partially received files, called the RC database. The RC database is loaded from disk when a Convert::yEnc object is created, and saved to disk when the object is DESTROY'd.