DDD Sample for https://twitter.com/naka_aki_spl/status/498700727942782976.

ddd_sample.rb

class Zzz
end

module XxxRole
  def behavior_as_x
    puts "zzz is xxx."
  end
end

module YyyRole
  def behavior_as_y
    puts "zzz is yyy."
  end
end

class XContext
  def initialize(zzz)
    @zzz = zzz
    @zzz.extend(XxxRole)
  end

  def execute
    @zzz.behavior_as_x
  end
end

class YContext
  def initialize(zzz)
    @zzz = zzz
    @zzz.extend(YyyRole)
  end

  def execute
    @zzz.behavior_as_y
  end
end

zzz = Zzz.new

x_context = XContext.new(zzz)
x_context.execute

y_context = YContext.new(zzz)
y_context.execute

Result

zzz is xxx.
zzz is yyy.