Yield items in AASM after callback

Question

Can you yield items inside an :after callback? I got LocalJumpException when I execute the code below

require 'aasm'
class TestClass
  include AASM
  aasm do
    state :created, initial: true
    state :running
    event :run do
      transitions from: :created,
      to: :running,
      after: proc { yield 1 }
    end
  end
end
TestClass.new.run! { |v| puts v }

score 0 · Accepted Answer · answered Dec 20 '18 at 16:13

It is impossible out of the box since aasm discards code blocks passed to event invocations, but hey, it’s ruby.

require 'aasm'
class TestClass
  include AASM
  aasm do
    state :created, initial: true
    state :running
    event :run do
      transitions from: :created,
      to: :running,
      after: -> { @λ_run.call(1) if @λ_run } # invoke the code block if was passed
    end
  end
end
TestClass.prepend(Module.new do
  def run!(*args, &λ)
    @λ_run = λ # store the code block passed to the method
    super
  end
end)
TestClass.new.run! { |v| puts v.inspect }

With a bit of meta-programming it should be easy to extend to all the defined event handlers.

Yield items in AASM after callback

1 Answers1