RapidFTR Addon

gistfile1.rb

# This is a marker for all addons, be it ExportTask or anything else
# All these will become class methods, and not instance methods
module Addon
  def enabled?
    @@enabled
  end
  
  def enable
    @@enabled = true
  end
  
  def disable
    @@enabled = false
  end
  
  def name
    # Name of the addon
    # Planning to make it as an i18n key rather than a string
  end
  
  def implementations
    descendants.select(&:enabled?)
  end
end

# The first addon interface
class ExportTask
  extend Addon
  # Now all Addon methods are class methods
  
  def self.name
    # Provide name (or i18n key)
  end
  
  def export(children)
    raise "Not Implemented"
  end
  
  class ExportResult
    attr_accessor :data, :content_type, :filename
  end
end

# The first implementation
class CPIMSExportTask < ExportTask
  def export(children)
    # Code...
  end
end

# The extension has to be enabled in an initializer
# config/initializers/addons.rb
CPIMSExportTask.enable

# Then to get list of Export Tasks,
ExportTask.implementations # Will return [CPIMSExportTask] if it was enabled

My alternative recommendation is here: https://gist.github.com/duelinmarkers/5547247