class select_based_event_system :unit ->sb_event_system
This the old Unix.select-based imeplementation of event systems
which was the default one until Ocamlnet-2.2.
Please avoid in new code. This module merely exists to allow comparisons between the old implementation and the new one.
Note that this class definition also includes some private methods. These are required in some other Unixqueue implementations inheriting from this class.
