eram / typescript-fsm Goto Github PK

https://github.com/eram/typescript-fsm/actions/runs/6901632913

Hello @eram, I really like the API design of your "typescript-fsm" library. It looks simple, yet powerful. I was wondering if it would be possible to generate the diagram of your "Basic Example" from the code?

One of the main reasons to use a FSM is to protect the internal state of the model (the context).
Normally the context is defined inside the FSM and is only accessible on transitions and onEnter/onExit executions (so you avoid side effects).

The only way to change the context of a FSM is sending an event to it.

Would be really nice to have conditional transitions.
Normally in a FSM you can define more than one transition for the same state/event and depending on the condition one transition is selected or not (first transition that fulfil a condition is chosen even if another transition would be a good candidate).

The transitions are evaluated on order of declaration.

The transition callbacks should receive and instance of the fsm event handler and the state from/to:

function onOpen(eh: EventHandler, from: State, to: State): Promise<void> {

    console.log("onOpen...");
    return eh.dispatch(Events.openComplete);
}

With your current code I would not be able to execute 2 instances of the same FSM, which is a problem if for example you want to use an FSM per user (to handle his user state).

Sometimes in a FSM is needed to just do something not on the transition but when you enter or exit one state. Would be nice to add this functionality.

Good example is your state "breaking" where you want only to log and you have to define the action for all the states that reach that state (would have more sense to do onEnter).

the example linked in the readme is broken
also, how do you generate the state machine chart there from typescript-fsm?

Hello!
@eram could You publish updated version to npm please?

Thanks.

Hi,

would you be open to a PR that adds strong types to the dispatch method?

Something like

StateMachine<STATE, EVENT extends string | number | symbol, CALLBACK extends Record<EVENT, Callback> = Record<EVENT, Callback>> {
 ...
  async dispatch<E extends EVENT>(event: E, ...args: Parameters<CALLBACK[E]>): Promise<void> {

and usage

interface ICallbacks extends Record<Events, Callback> {
  [Events.open]: (test: number) => void;
  [Events.close]: (te: string) => void
}

class Door extends StateMachine<States, Events, ICallbacks> {