CalendarIfc

The interface defines behavior for holding, adding and retrieving events. The executive uses one calendar, supplied to the model, to find the next event to run.

Canceling is lazy, in every shipped calendar. Setting KSLEvent.cancel to true only marks the event, and the event stays in the calendar until its time comes, when the executive drops it. This avoids rebuilding the underlying structure, and it costs nothing unless a model cancels very many events far in the future, which then stay in memory. A model that does so can supply a calendar that purges them.

A calendar must:

• be used by one model only, since it holds that model's events;

• return events in their natural order, by time, then priority, then order of scheduling;

• keep returning canceled events, or remove them itself, since it isn't told about a cancellation and has to read KSLEvent.cancel;

• remove everything in clear(), which the executive calls to reset the calendar.

Inheritors