run method

_MessageAction<M> run(
  1. FutureOr<void> action(
    1. MessageContext msgCtx,
    2. M msg
    ), {
  2. String? label,
})

Runs the action while a message is being handled.

When the action function is called, it is passed a MessageContext, and the message that is being handled.

void onMessage<M>(MessageContext ctx, M message) => print('Handling message');

var state1 = StateKey('s1');
var state2 = StateKey('s2');
var builder = StateTreeBuilder(initialState: state1);

builder.state(state1, (b) {
  // Calls the onMessage function as a side effect before the transition occurs
  b.onMessage<MyMessage>((b) => b.goTo(state2, action: b.act.run(onMessage);
});

This action can be labeled when formatting a state tree by providing a label.

Implementation

_MessageAction<M> run(
  FutureOr<void> Function(MessageContext msgCtx, M msg) action, {
  String? label,
}) {
  return _MessageAction<M>._(_ActionType.run, (msgCtx, msg) {
    _logger.fine(() => "State '$_forState' is running a message action.");
    action(msgCtx, msg);
  }, null, label);
}