如何使模块包含在类中 [英] How to get the modules included in a class

问题描述

请注意， ancestors

code>，< => ， included_modules 将无法工作，因为他们的结果不区分模块都包含在超类前面的模块中。换句话说，他们无法区分以下两种情况：

• M 被添加到 B

    end 
   class B<一个; 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

    end 
   class B<一个; end 
   module M; end 
   B.include M 
   
   B.ancestors＃=> [B，M，A，Object，Kernel，BasicObject] 
   B< => M＃=> -1 
   B.included_modules＃=> [M，Kernel] 
    

解决方案

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

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]
  

解决方案

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

这篇关于如何使模块包含在类中的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！