How to get the modules included in a class

问题

How can I get an array of modules included in a class, excluding those that slipped in through inheritance?

Notice that ancestors, <=>, included_modules will not work because their results do not distinguish modules that are included from modules that are prepended in a superclass. In other words, they cannot distinguish the following two cases:

• M is prepended to the superclass of B

  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 is included in B

  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]
  

回答1:

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

来源：https://stackoverflow.com/questions/34484006/how-to-get-the-modules-included-in-a-class