Exploring rtwomey/stately

stately_demo_bad.rb

#!/usr/bin/env ruby

=begin
This is an example of limitations of the present stately gem.  

1. What appear to be instance variables within the Order class (i.e. @count) are not, they
   seem to be instance variables of some class State or Machine or ??? which is part of
   the underlying implementation of the machine.

2. Examples don't show the need to have requires (a newbie issue only)

3. The instance variable state had to be created to avoid an error message.
=end


require 'rubygems'
require 'stately'

class Order

  attr_accessor :count, :state

  def initialize
    @count = -1
  end

  stately start: :processing do
    state :started do
      @count = 0
      puts "@count = #{@count}"
    end

    state :incremented, action: :increment do
      @count = 1
      puts "@count = #{@count}"
    end
  end

  def count
    @count
  end
end

order = Order.new
order.start
order.increment
puts "order.count = #{order.count}"
puts "order.state = #{order.state}"

stately_demo_good.rb

require 'rubygems'
require 'stately'

class Order

  attr_accessor :state, :count

  stately start: :processing do
    state :started do
      after_transition do: :zero_count
    end

    state :incremented, action: :increment do
      after_transition do: :increment_count
    end

    state :waiting, action: :wait

  end

  def zero_count
    @count = 0
  end

  def increment_count
    @count += 1
  end

end

order = Order.new
order.start
order.increment
order.wait
order.increment
puts "order.state = #{order.state}"
puts "order.count = #{order.count}"