PersistenceDeleagate - alternative to persistent

PersistenceDeleagate is an another solution for persistent. This technique has two advantages:

1. Persistence function is separated to the third-party - the PersistenceDelegate, but not the object itself. This way, the deserialized form is no longer an integrated part of object public interface.

2. If developer is not owner of some class, he/she still can easily persist instances of the class.

The hard part is, some developer tend not to provide corresponding delegater, which make the default one hard to implement

Legend of Mainframe

The ancestor of mainframe computer are IBM 705 & IBM 1401. They respectively born in 1954 and the last year of the fifties of last century. These two machines are primarily now served as central data repository.
Then comes system 360 (s/360) - The third generation computer. It is the first general purpose computer. At this time, manufactures tended to standardize the HW & SW they offered to customers.

ls -t

ls -t sort files according to last modification date in descending order which is handy when finding out the latest modified files.