[Feature] Clustering and non-hierarchical state relationships about xstate HOT 4 CLOSED

It should be noted that this is from the possible extensions to the formalism chapter, and not part of the original formalism per se. SCXML and most other have them as explicitly hierarchical, so I'm not too keen on this :) "after 2s" is way higher on my list!

Other than that, I haven't experienced the need for it. Yes, there might be portions of a statechart that need to be duplicated (e.g. that α and β arrows need to be duplicated in the C state), I'm thinking that there might be better ways of dealing with that, other than overlapping states. Maybe reusable chunks of on handlers when defining the state machine itself.

const handleAlpha = { "α", "elsewhere1"}
const handleBeta = { "β": "elsewhere2" };

const states = {
  A: {
    on: handleAlpha,
    states: {
      B: {}
      C: { on: hanldeBeta}
    }
  }
  D: {
    on: handleBeta,
    states: {
      E: {}
      F: {}
      C: { on: hanldeAlpha}
    }
  }
}

The spread operator could be used to combine many signals.

from xstate.

That's true - I'll mark this as Documentation so that we can just show how this can be accomplished with ES6.

from xstate.

I'd still like to support this eventually - although it can be accomplished with ES6 language features, you lose the details of states being related, and that's important meta information to have when visualizing the statecharts.

from xstate.

I can;t find the reference for the paper but this feature had been investigated by Harel and they discarded it because of the added complexity, the perceived lower readability and the lack of actual use cases. aah found it :

One is the notion of overlapping states,
whereby you want the and/or state hierarchy in statecharts
to be a directed graph, not a tree. (...) We found that
the issue was pretty complicated since, e.g., overlapping
can be intermixed not only with the substate facet of the
hierarchy but also with orthogonal components. We
actually concluded that the complications might outweigh
the benefits of implementing the feature.

from xstate.