How can I reverse ruby's include function

Question

I'll explain what i'm looking for in code as thats probably the most succinct:

module Mixin   def method     puts "Foo"   end end  class Whatever   include Mixin end  w = Whatever.new w.method => "Foo"  # some magic here w2 = Whatever.new w.method => NoMethodError 

I had tried just undefining the Mixin module using remove_const, but this doesn't seem to make any difference to Whatever. I had assumed that #include just added a reference to the module into the class's method resolution chain - but this behaviour doesn't agree with that.

Can anyone tell me what include actually does behind the scenes, and how to reverse this?

Answer 1

As it seems probably you want to accomplish these on instances instead of the whole class, so I would change klochner's code a bit to handle just one instance instead of all the instances of a class.

module ModuleRemover      def remove_module(mod, options = {})       metaclass = class << self; self end       mod.instance_methods.each {|method_name| metaclass.class_eval { undef_method(method_name.to_sym) }}     end  end 

As Mladen pointed out, it would be cool to avoid removing methods that are overwritten on the host class, so an [only, exclude] options for this method would be ideal.

>> c1 = C.new >> c1.foo => fooing >> c1.extend(ModuleRemover) >> c1.remove_module(Mod) >> c1.foo => NoMethodError: undefined method `foo' for #< C:0x11b0d90> >> c2 = C.new >> c2.foo => fooing 

Answer 2

module Mod   def foo     puts "fooing"   end end  class C   include Mod   def self.remove_module(m)     m.instance_methods.each{|m| undef_method(m)}   end end  >> c = C.new >> c.foo fooing >> C.remove_module(Mod) => ["foo"] >> c.foo NoMethodError: undefined method `foo' for #&lt C:0x11b0d90>