observer.rb

class CriminalMovement
  include Observable

  attr_reader :criminal
  def initialize(criminal)
    @criminal = criminal
  end

  def action(msg)
    changed
    notify_observers(criminal, msg)
  end
end

class Criminal
  attr_reader :name
  
 
def initialize(name)
    @name = name
  end
end

class FbiMovement
  attr_reader :fbi
  def initialize(fbi)
    @fbi = fbi
  end

  def update(criminal, msg)
    p criminal.name + msg + ‘: ‘ + fbi.name + ‘收到‘
  end
end

class Fbi
  attr_reader :name
  def initialize(name)
    @name = name
  end
end

 
# 臥底
class Dinting
  def self.run
    crmn1 =  Criminal.new(‘黑狗‘)
    crmn2 =  Criminal.new(‘黑虎‘)

    fbi1 = Fbi.new(‘飛鷹1號‘)
    fbi2 = Fbi.new(‘飛鷹2號‘)

    fbi1_observer = FbiMovement.new(fbi1)
    fbi2_observer = FbiMovement.new(fbi2)
    crinimal1_observer = CriminalMovement.new(crmn1)
    crinimal2_observer 
 
= CriminalMovement.new(crmn2)

    fbi_observers = [fbi1_observer, fbi2_observer]
    crinimal_observers = [crinimal1_observer, crinimal2_observer]

    fbi_observers.each do |fbi_o|
      crinimal_observers.each do |cri_o|
        cri_o.add_observer(fbi_o)
      end
    end

    crinimal1_observer.action(‘今天淩晨2點，南河小巷搶劫‘)
    crinimal2_observer.action(‘明天淩晨2點，愛河毒品交易‘)
  end
end

Dinting.run

程序運行結果：

Ruby設計模式-觀察者模式學習筆記