[core] Add actor.onStop(…)

[davidkpiano]

Added onStop handler to actors which allows registering callbacks that will be executed when an actor is stopped. This provides a way to perform cleanup or trigger side effects when an actor reaches its final state or is explicitly stopped.

const actor = createActor(someMachine);

actor.onStop(() => {
  console.log('Actor stopped');
});

[changeset-bot]

🦋 Changeset detected

Latest commit: daf332d

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 6 packages

Name	Type
xstate	Minor
@xstate/graph	Major
@xstate/react	Major
@xstate/solid	Major
@xstate/svelte	Major
@xstate/vue	Major

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[tnortman-jabra]

Any way for there to be some way to handle this in the state machine configuration itself?

For example:

setup({
  actions: {
    criticalAction: () => { 
       // iWantToRunOnTeardownNoMatterWhat 
    },
  },
}).createMachine({
  stop: 'criticalAction',
});

[Andarist]

@tnortman-jabra it already exists (sort of):

import { setup, fromCallback } from "xstate";

setup({
  actors: {
    criticalCleanup: fromCallback(() => () => {
      // do stuff
    }),
  },
}).createMachine({
  invoke: {
    src: "criticalCleanup",
  },
});