Module: Smash::CloudPowers::WorkflowFactory

Included in:
Smash::CloudPowers
Defined in:
lib/cloud_powers/workflow_factory.rb

Overview

The WorkflowFactory module provides you with a custom, embeddable workflow for classes. To do this, it takes a description of the workflow, in the form of a Hash and injects it into the class' Singleton/Eigan class. It uses the workflow gem to handle the workflow stuff for now but after MVP, this will be a roll-our-own implementation, to cut down on all dependencies possible.

Instance Method Summary collapse

Instance Method Details

#description_to_s(description) ⇒ Object

Takes a description and turns it into a string that would describe the workflow you want to insert.

Parameters

  • description Hash - of the format { workflow: { states: [ { state_name: { event: :event_name, transitions_to: :transition_to_name } }, { state_name: nil } ] } }

Returns String

Example

given the description seen in inject_workflow()

puts description_to_s(description)

=>

workflow do state :new do event :build, :transitions_to => :building end state :building do event :run, :transitions_to => :in_progress end state :in_progress do event :post_results, :transitions_to => :done end state :done end Notes

  • See inject_workflow()


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# File 'lib/cloud_powers/workflow_factory.rb', line 140

def description_to_s(description)
  description_string_builder = ['include Workflow', 'workflow do']
  description[:workflow][:states].each do |state|
    state.map do |name, state_description|
      if state_description.nil? # if this is a final state...
        description_string_builder << "state :#{name}"
      else # because it is not a final state, add event information too.
        description_string_builder.concat([
          "state :#{name} do",
          "event :#{state_description[:event]}, transitions_to: :#{state_description[:transitions_to]}",
          "end"
        ])
      end
    end
  end
  description_string_builder << "end\n"
  description_string_builder.join("\n")
end

#inject_workflow(description) ⇒ Object

This is the method responsible for injecting the workflow on the instance it is called on. After this method is called on an instance of some class, you can then access any of the described states as methods on that instance.

Parameters

  • description Hash - Describe the workflow you want to use. The format follows the actual Workflow Specification(s) from the gem that you would normally write onto the class like normal.

  • Example description Hash

    • this description would give you a workflow that starts in the new state and when the #build!() method was called on the object that has this workflow, the state would transition into the building state. The workflow would then listen for the run!() method call, which would progress the state to the in_progress state. Next, the workflow would listen for the post_results!() method call. When someone or something calls it, the state will progress to the final state, done, from which no more workflow stuff will happen.

      description = { workflow: { states: [ { new: { event: :build, transitions_to: :building } }, { building: { event: :run, transitions_to: :in_progress } }, { in_progress: { event: :post_results, transitions_to: :done } }, { done: nil } ] } }

Returns

  • nil

Example

  • build the workflow using the description from above class Job # code code code... def insert_my_workflow(description) class << build_workflow(description) end end

    Which would yield this workflow, from the Workflow gem

    class Job
# all the commented lines below are what `WorkflowFactory#inject_workflow()`
# did for you.  These lines don't need to actually be in your class.

# include Workflow
#
# workflow do
#   state :new do
#     event :build, :transitions_to => :building
#   end
#   state :building do
#     event :run, :transitions_to => :in_progress
#   end
#   state :in_progress do
#     event :post_results, :transitions_to => :done
#   end
#   state :done
# end
end

job = Job.new
# => #<Job:0x007fdaba8956b0>
job.done?
# => NoMethodError
job.insert_workflow(description)
# => nil
job.done?
# => false
job.current_state
# => :building

Notes

  • See description_to_s()
  • TODO: There has got to be a better way, so if any of you have suggestions... The fact that the eval gets evaluated and invoked in the workflow gem is of little comfort, despite how nice the gem is. Long story short, be comfortable with what you're doing.
  • see the workflow gem docs and question me if you want some nice ways to really use this module. workflow homepage


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# File 'lib/cloud_powers/workflow_factory.rb', line 95

def inject_workflow(description)
  workflow_spec_string = description_to_s(description)
  begin
    self.class.class_eval(workflow_spec_string)
    define_singleton_method(:has_workflow?) { true }
  rescue Exception => e
    define_singleton_method(:has_workflow?) { !!(puts e.backtrace) }
  end
end