From: Su Zhang <su.comp.lang.ruby@...>
Date: 2011-12-02T15:57:09+09:00
Subject: Inverse Operation of Module#include

Hi list,

Is there a built-in inverse operation of Module#include? Currently I have:

class A
end

module B
   def foo
     :b
   end
end

module C
   def foo
     :c
   end
end

a = A.new

class A
   include B
end
p a.foo # => :b

class A
   include C
end
p a.foo # => :c

class A
   include B
end
p a.foo # => :c

So if module B has already been mixed in, it cannot be re-included again 
thus the foo method is not redefined to B#foo in the last include 
operation. Thus occurs to me when I use Inversion of Control (or 
dependency injection) to switch between various implementations of a 
certain interface. I was thinking that if I can somehow "exclude" the 
module and include it again then the problem would be solved, and hence 
the question.

Or better yet, is there another way to achieve this kind of 
implementation switching?

Regards,

Su