ruby-on-rails – 如何在Ruby / Rails中重新打开模块

module Greetings
   def self.greet(message)
      return "good morning" if message=="gm"
      return "evening" if message=="ge"
      return "good afternoon" if message=="ga"
   end
end

当我做Greetings.greet(“ge”)时,我将“晚上”作为输出.我想改变这种行为而不改变上面的Greetings模块(显而易见的原因是它是一个外部插件).

我的问题很简单.当我打电话给Greetings.greet(“ge”)时,我应该怎么做才能给我回复“A Very Good Evening”,对于所有其他输入,它应该返回原始模块返回的内容.

我会在config / initializers文件夹中写这个,因为我正在使用Rails.

PS：我已经为课程筹集了similar question.但我真的想知道模块是如何工作的.

module Greetings
   def self.greet(message)
      return "good morning" if message=="gm"
      return "evening" if message=="ge"
      return "good afternoon" if message=="ga"
   end
end

p Greetings.greet("ge") # => "evening"

module Greetings
  class << self
    alias_method :old_greet, :greet

    def greet(message)
      return self.old_greet(message) unless message == "ge"
      return "A Very Good Evening"
    end
  end
end

p Greetings.greet("ge") # => "A Very Good Evening"
p Greetings.greet("gm") # => "good morning"