ruby – 通过在另一个模块中混合来覆盖模块Mixin行为

我希望能够来回切换实例如何响应消息.我希望通过混合模块,然后在另一个模块中混合以覆盖该行为来实现.

例：

module Dog
  def speak
    puts "woof woof"
  end
end

module Cat
  def speak
    puts "meow"
  end
end

class Animal
end

现在我想来回切换,Animal的一个实例如何响应发言信息：

animal = Animal.new

animal.extend(Cat)
animal.speak

animal.extend(Dog)
animal.speak

animal.extend(Cat)
animal.speak

animal.extend(Dog)
animal.speak

animal.extend(Cat)
animal.speak

我希望此代码输出以下内容：

meow
woof woof
meow
woof woof
meow

相反,它输出如下：

meow
woof woof
woof woof
woof woof
woof woof

有关如何使其按预期工作的任何提示？

解决方法

我在 Adapter Pattern in ruby: Accessing Your Instance Variables的另一个问题上修改了答案

module Dog
  def speak
    puts "woof woof"
  end
end

module Cat
  def speak
    puts "meow"
  end
end

module Module_manager
  attr_accessor :name
  def extend mod
    @ancestors ||= {}
    return if @ancestors[mod]
    remove @name if @name
    @name = mod
    mod_clone = mod.clone
    @ancestors[mod] = mod_clone
    super mod_clone
  end

  def remove mod
    mod_clone = @ancestors[mod]
    mod_clone.instance_methods.each {|m| mod_clone.module_eval {remove_method m } }
    @ancestors[mod] = nil
  end
end

class Animal
  include Module_manager
end

animal = Animal.new

animal.extend(Cat)
animal.speak # meow

animal.extend(Dog)
animal.speak # woof woof

animal.extend(Cat)
animal.speak # meow

animal.extend(Dog)
animal.speak # woof woof

animal.extend(Cat)
animal.speak # meow