Ruby代理例子

require 'delegate'

class Assistant
 def initialize(name)
  @name = name
 end

 def read_email
  puts "(#{@name}) It's mostly spam."
 end

 def check_schedule
  puts "(#{@name}) You have a meeting today."
 end
end

class Manager < DelegateClass(Assistant)
 def initizlize(assistant)
  super(assistant)
 end

 def attend_meeting
  puts "please hold my calls"
 end
end

frank = Assistant.new("Frank")
anne=Manager.new(frank)
anne.attend_meeting   #=> please hold my calls
anne.read_email      #=>(Frank) It's mostly spam.
anne.check_schedule   #=>(Frank) You have a meeting today.

=begin
DelegateClass()是一种拟态方法,这种方法创建并返回一个新的Class..这个类会定义一个method_()方法,并把对它发生的调用转发到被封装的对象上,比如本例的Assistant对象. Manager类会继承这个method_missing()方法,因此它就成为被封装对象的一个代理.结果,Manager就会把自己无法识别的方法转发给它封装的Assistant.
=end