d--j/em-ftpd — comment on commit af9fa29088f0be8eda39abd05d42be4efc549d17
File:  line 0
By d--j:

Usecases:
A virtual file system that depends on the user that is logged in (User A sees folder one and two, user B only sees folder three).
Or saving some temporary data that is connection/user-specific (like an authentication token or some sort of cache).

I have a driver that connects to a web service. It uses both use cases (per user virtual file system and authentication token for authenticating the web requests).

The connection could store the state but it is the driver that needs to know about it. So the connection would have to pass the state along to the driver for every method call.