[Enhancement] Add declarative syntax for delegated context variables

[William Pollet]

Sometimes we instantiate objects manually in the actor, from a main input. To do that, most of the time we override the call method in the players, or create attr_readers from the main input.

What do you think about adding a declarative syntax to avoid being forced to override call in such use cases ?

An actor looking like this

module Projects
  class Confirm < Actor
    input :project, type: Project

    def call
      result.owner = project.owner
      result.rewards = project.rewards

      super
    end

    play ConfirmOwner, ConfirmRewards, ConfirmProject
  end
end

Could be simplified like this for instance :

module Projects
  class Confirm < Actor
    input :project, type: Project

    declare :owner, :rewards, on: :project

    play ConfirmOwner, ConfirmRewards, ConfirmProject
  end
end

[Sunny Ripert]

Hey @williampollet \o/

I think in that case I would go with the more versatile lambdas, that allows to be inserted in between actors, e.g.:

module Projects::Confirm < Actor
  input :project, type: Project

  play -> result {
         result.owner = result.project.owner
         result.rewards = result.project.rewards
       },
       ConfirmOwner,
       ConfirmRewards,
       ConfirmProject,
       -> result { result.moderator = result.project.moderator },
       NotifyModerator
end

Adding a new DSL to declare this would be a bit too much for this gem I think.