如何将模块包含在类中

Question

如何获取类中包含的模块数组，不包括那些通过继承传入的模块？

请注意ancestors，<=>，included_modules不起作用，因为它们的结果不区分包含在超类中预先添加的模块中的模块。换句话说，他们无法区分以下两种情况：

• M前置于B

  的超类

  class A; end
  class B < A; end
  module M; end
  A.prepend M
  
  B.ancestors # => [B, M, A, Object, Kernel, BasicObject]
  B <=> M # => -1
  B.included_modules # => [M, Kernel]
  

• M包含在B

  中

  class A; end
  class B < A; end
  module M; end
  B.include M
  
  B.ancestors # => [B, M, A, Object, Kernel, BasicObject]
  B <=> M # => -1
  B.included_modules # => [M, Kernel]
  

Answer 1

mixed_in  = B.included_modules[0...-B.superclass.included_modules.size]
prepended = B.ancestors.take_while { |ancestor| ancestor != B }
included  = mixed_in - prepended