Question

module Superpower      # instance method     def turn_invisible         ...     end      # module method     def Superpower.turn_into_toad         ...     end      module Fly         def flap_wings             ...         end     end  end  Class Superman     include Superpower     ...      def run_away         # how to call flap_wings?         # how to call turn_invisible?     end      def see_bad_guys(bad_guy = lex_luthor)         #is this correct?         Superpower.turn_into_toad(bad_guy)     end end 

Hi I saw some ruby code which I couldn’t understand. How do you call flap_wings from within the Superman class? Is it possible to call an instance method from within the class? What is the difference between including modules and embedding modules? Why and when should you do that?

Answer 1

I’m assuming that when you say embedding a module you mean the ‘Fly’ module from your example is embedded in ‘Superpower’.

If that is the case, I would call it a nested module. The only time I would use a Nested Module is when the nested module deals specifically with the main module, such that the code in Fly is directly correlated to Superpower, but are separated for convenience and readability.

You can use the nested module’s methods simply by including superpower first, then fly second, like so:

Class Superman     include Superpower     include Fly     # ... end 

The details are described further on this blog.