Widened the *From utility types to allow extracting from factory functions

[mattpocock]

Copied from changeset:

Widened the *From utility types to allow extracting from factory functions.

This allows for:

const makeMachine = () => createMachine({});

type Interpreter = InterpreterFrom<typeof makeMachine>;
type Actor = ActorRefFrom<typeof makeMachine>;
type Context = ContextFrom<typeof makeMachine>;
type Event = EventsFrom<typeof makeMachine>;

This also works for models, behaviours, and other actor types.

[changeset-bot]

🦋 Changeset detected

Latest commit: 6d284fe

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

This PR includes changesets to release 1 package

Name	Type
xstate	Patch

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[davidkpiano]

Really useful change. Wondering if it would be too much abstraction to have a type like this?

type FactoryOrValue<T> = T extends ((...args: any[]) => infer U) ? U : T;

Then we can do:

export type StateFrom<T> = FactoryOrValue<T> extends StateMachine<any,any,any>
  ? FactoryOrValue<T>['transition']
  : ...

Just thinking out loud 🤔

[davidkpiano]

We can get this merged in after tests are passing (I can help investigate)

[davidkpiano]

Is the idea to add to this extends whenever we add a new thing that StateFrom can extract a state from?

[mattpocock]

Yes, that will work.

[Andarist]

I've removed this on my branch - https://github.com/mattpocock/xstate/pull/1/files . I don't have super strong opinion about this and definitely having those constraints in place could improve where type errors are reported and so on. We didn't have those in other *From utilities - so I've just gone for the unification for the time being. We can always unify this other way around - although keeping the list of those things is a little bit tedious 🤷‍♂️

[mattpocock]

Really useful change. Wondering if it would be too much abstraction to have a type like this?

type FactoryOrValue<T> = T extends ((...args: any[]) => infer U) ? U : T;

Then we can do:

export type StateFrom<T> = FactoryOrValue<T> extends StateMachine<any,any,any>
  ? FactoryOrValue<T>['transition']
  : ...

Just thinking out loud 🤔

Probably a good idea? I'm really nervous to do stuff like this in a codebase that doesn't have strict: true in it, but it would probably work.

[mattpocock]

@davidkpiano Tried the above, doesn't work

[Andarist]

Re FactoryValue - I have tried a slightly different approach and it seems to work: https://github.com/mattpocock/xstate/pull/1/files . It would be great to add some tests for this though.

[davidkpiano]

Re FactoryValue - I have tried a slightly different approach and it seems to work: https://github.com/mattpocock/xstate/pull/1/files . It would be great to add some tests for this though.

Nice; well, we can do refactor later. I think this is good to go in, wdyt?

[Andarist]

Nice; well, we can do refactor later. I think this is good to go in, wdyt?

Well, sure - but since it's already implemented, wouldn't it be easier to review it, merge to this one and then land on the main branch?

[davidkpiano]

Nice; well, we can do refactor later. I think this is good to go in, wdyt?

Well, sure - but since it's already implemented, wouldn't it be easier to review it, merge to this one and then land on the main branch?

Sure, that sounds good to me