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