Plug-in question: define a module first or just open the class definition?

I notice that some plug-ins first do something like:
  module MyPlugin
    def do_something_very_funky
    end
  end

and than include this into one of Rails' existing classes (often in the
same file).

  module ActionController
    class Base
       include MyPlugin
    end
  end

Is there any advantage to this compared to simply doing:

  module ActionController
    class Base
      def so_something_very_funky
      end
    end
  end

I can't think of any myself.

Read the chapter on Classes and Modules in Programming Ruby by Dave
Thomas. Then read the Rails Plugin - Extending the Rails Core
Functionality by James Adam for an indepth coverage on plugins.

Well, I read that chapter before I started this thread :slight_smile:

I don’t think you can use the same name ActionController for your module. The main idea here is that you once you define a module with your methods in it, you can mix-in any of the classes that you wish.

It gives you a multiple-inheritance like behaviour. It provides namespace also.

I understand which purpose modules serve. My question, however, was if
there's any
advantage to defining a module for no other purpose than extending a
particular class
instead of just directly changing that class. I hope I didn't add more
confusion to my
already vague question.

Thank your very much for your clear description of the pros and cons of
each
approach. This was a much more detailed explanation than I could have
ever
hoped for. :smiley: