获取包含模块的类的列表

问题描述

我有一个mixin，我想获取一个包含它的所有类的列表.在mixin模块中，我执行了以下操作:

I have a mixin for which I would like to get a list of all the classes that have included it. In the mixin module, I did the following:

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

  def self.classes
    @classes
  end
end

class MyClass
  include MyModule
end

这很好用:

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

现在，我想将此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.因此，我提出了以下建议:

Now, I would like to extract this part out into a separate module that can be included in my other mixins. So, I came up with the following:

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，它确实已将#classes成功添加到MyModule.

This doesn't work though, because the #included(module_base) method being added to MyModule from ListIncludedClasses is never getting run. Interestingly enough, it does successfully add #classes to 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

我想念什么?

推荐答案

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]

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