nested states

[Bill Burcham]

I have "succeeded" and "failed" states that both represent "completed" states. The traditional way to represent that in a state transition diagram is with nested states: "succeeded" and "failed" nest under "completed". This might introduce the notion of multiple simultaneous states e.g. "failed"/"completed", "succeeded"/"completed".

The way I am handling this now is by explicitly modeling the compound state and synthesizing a predicate for it (completed?):

complete_states = [:succeeded, :failed]

state_machine do

  state all - complete_states do

    def complete?

      false

    end

  end

  state *complete_states do

    def complete?

      true

    end

  end

  after_transition any => complete_states do

     do_stuff!

  end

  ...

The predicate method pair is a bit not-DRY but perhaps worse is that my (graphviz) diagram doesn't nest "succeeded"/"failed" under "completed".

Am I doing this right or is there a better way with state_machine?

[Bill Burcham]

BTW the project where I'm doing the "nested states" is called orchestrated. It's a lightweight workflow orchestration gem that runs atop delayed_job.

Github: (docs including Graphviz output of states) https://github.com/paydici/orchestrated

Rubygems: https://rubygems.org/gems/orchestrated