round.rb

class CreateprogramDependencies < ActiveRecord::Migration
  def self.up
    create_table :program_dependencies do |t|
      t.references :dependency, :polymorphic => true
      t.references :program
    end
  end

  def self.down
    drop_table :program_dependencies
  end
end


class Program < ActiveRecord::Base
  has_many :program_dependencies
  has_many :dependencies, :through => :program_dependencies

  has_many :dependent_program_dependencies, :class_name => "ProgramDependency", :as => :dependency
  has_many :dependent_programs, :through => :dependent_program_dependencies, :source => :program
end

class ProgramDependency < ActiveRecord::Base
  belongs_to :program
  belongs_to :dependency, :polymorphic => true
end

class Component < ActiveRecord::Base
  has_many :program_dependencies, :as => :dependency
  has_many :dependencies, :through => :program_dependencies
end