gistfile1.rb

# app/models/queue/base.rb
class Queue::Base

  class << self

    def enqueue(object, method, *args)
      # ...to be continued
    end

    def perform
      # ...to be continued
    end
  end
end

# app/models/queue/high.rb
class Queue::High < Queue::Base
  @queue = :high
end

# app/models/queue/normal.rb
class Queue::Normal < Queue::Base
  @queue = :normal
end

# app/models/queue/low.rb
class Queue::Low < Queue::Base
  @queue = :low
end