Summary

This PR introduces a Schedule dataclass to centralize recurring event configuration and refactors EventGenerator to use it. The change simplifies the event-generation API, consolidates stop/start behavior, and improves clarity around recurring execution rules.

A new stable API for creating events and running will still be introduced in another PR, this PR just builds the foundation for that. See EwoutH@440fdbe for an initial concept.

Motive

Previously, EventGenerator handled interval logic, start timing, and stop conditions (at, after, count) internally. This created a more complex API surface and scattered scheduling logic across multiple methods.

Implementation

A new Schedule dataclass was introduced to define recurring execution behavior (interval, start, end, and count). The interval field supports both fixed numeric values and callables evaluated against the model at runtime.

EventGenerator was refactored to depend on Schedule instead of storing interval and stop-condition state internally. The generator now reads execution limits directly from the schedule when determining whether to reschedule events. The start() method was simplified to use schedule.start or default to model.time + interval, and stop() now performs only immediate cancellation.

Tests were updated to reflect the new API, and a new test suite for Schedule was added. Existing behavior such as callable intervals, execution counting, and priority ordering remains covered.

Usage Examples

# Basic recurring generator
gen = EventGenerator(model, fn, Schedule(interval=1.0, start=0.0))
gen.start()

# schedules
schedule = Schedule(interval=1.0, start=0.0, count=5)
schedule = Schedule(interval=1.0, start=0.0, end=10.0)
schedule = Schedule(interval=lambda m: m.time * 0.5, start=0.0)

# using schedule
EventGenerator(model, fn, schedule).start()

Additional Notes

• The Schedule object can be used for other things too, like data collection schedules (see Add DataRecorder for reactive Data Storage and DatasetConfig for Configuration #3145 (comment), cc @codebreaker32).
• This PR introduces a small API break in EventGenerator by replacing the interval argument with Schedule.
• Stop conditions are now declarative via Schedule instead of configured at runtime.
• The generator lifecycle is now simpler: start() activates scheduling, stop() cancels immediately.
• Test coverage for DEVS scheduling behavior has been expanded.