From: Pit Capitain <pit@...>
Date: 2007-03-01T04:29:24+09:00
Subject: Re: How to get modules included by a class/module (not those from the superclasses)

Ruby Admirer schrieb:
> Is there a way to get only the modules included by a given class. 
> Using included_modules returns also the modules that are included by 
> the superclass(es).
> (...)
> As a given module may be included several times in the class
> hierarchy (e.g. by the class and by one of its superclass), just
> getting all included modules and removing the included modules from
> the superclasses may not be a solution. The given module may have
> been removed erroneously.

Including a module in a class that already has been included by one of 
its superclasses doesn't change the inheritance hierarchy:

   module M
   end

   class P
     include M
   end

   class C < P
   end

   p C.ancestors  # => [C, P, M, Object, Kernel]

   class C
     include M
   end

   p C.ancestors  # => [C, P, M, Object, Kernel]

The only way to create the situation you describe above would be to 
include the module in the child class *before* including it in the 
superclass. If you want to detect this, you could try the following code:

   class Class
     def my_own_included_modules
       ancestors.inject([]) { |acc, mod|
         break acc if mod == superclass
         acc << mod unless mod == self
         acc
       }
     end
   end

   p P.my_own_included_modules  # => [M]
   p C.my_own_included_modules  # => []

   class P2
   end

   class C2 < P2
     include M
   end

   class P2
     include M
   end

   p C2.ancestors  # => [C2, M, P2, M, Object, Kernel]

   p P2.my_own_included_modules  # => [M]
   p C2.my_own_included_modules  # => [M]

Out of curiosity: why do you need this?

Regards,
Pit