# Class Uq_engines.signal_engine

    class ['a] signal_engine : Unixqueue.event_system -> object .. end

`let se = new signal_engine esys`: The engine `se` remains in ``Working 0` until the method `se # signal x` is called. At this point `e` transitions to `x`. Any further call of `signal` does not have any effect.

Also, if `se` is aborted, `signal` does not have any effect.

The function `signal` may be called from a different thread. The signalling event is forwarded to the thread running the event system.
Inherits

- `Uq_engines.engine`

    method signal : 'a final_state -> unit