获取包含模块的类列表

Question

我有一个mixin,我想获得包含它的所有类的列表.在mixin模块中,我做了以下事情:

module MyModule
  def self.included(base)
    @classes ||= []
    @classes << base.name
  end

  def self.classes
    @classes
  end
end

class MyClass
  include MyModule
end

这非常有效:

> MyModule.classes #=> nil
> MyClass.new #=> #<MyClass ...>
> MyModule.classes #=> ["MyClass"]

现在,我想将这部分提取到一个单独的模块中,该模块可以包含在我的其他mixins中.所以,我想出了以下内容:

module ListIncludedClasses
  def self.included(base)
    p "...adding #{base.name} to #{self.name}.classes"

    @classes ||= []
    @classes << base.name

    base.extend(ClassMethods)
  end

  def self.classes
    @classes
  end

  module ClassMethods
    def included(module_base)
      p "...adding #{module_base.name} to #{self.name}.classes"

      @module_classes ||= []
      @module_classes << module_base.name
      super(module_base)
    end
    def classes
      @module_classes
    end
  end

end

module MyModule
  include ListIncludedClasses
end

但这不起作用,因为从ListIncludedClasses添加到MyModule的#included(module_base)方法永远不会运行.有趣的是,它确实成功地将#classes添加到了MyModule.

> MyModule.classes #=> 
  "...adding Rateable to ListIncludedClasses.classes"
  => nil 
> ListIncludedClasses #=> ["MyModule"]
> MyClass.new #=> #<MyClass ...>
# ^^ THIS SHOULD BE ADDING MyClass TO MyModule.classes ^^
> MyModule.classes #=> nil

我错过了什么？

Answer 1

module MyMod; end

class A; include MyMod; end
class B < A; end
class C; end

ObjectSpace.each_object(Class).select { |c| c.included_modules.include? MyMod }
  #=> [B, A]