abomination.rb

module Abominate
  def replace_object new_object
    raise Exception.new( "Ia! Ia! Cthulhu Fhtagn!" ) unless instance_variable_defined? "@i_know_this_is_an_abomination"

    context = class << self ; self ; end

    new_object.instance_variables.each do |var|
      instance_variable_set( var, new_object.instance_variable_get( var ) )
    end

    instance_variables.each do |var|
      remove_instance_variable( var ) unless new_object.instance_variable_defined? var
    end

    self.methods.each do |method_name|
      meth = method_name.to_sym

      unless new_object.respond_to? meth then
        context.instance_eval do
          define_method meth do
            raise NoMethodError.new( "undefined method `#{ method_name }' for #{ self.inspect }:#{ new_object.class }" )
          end
        end
      end
    end

    new_object.methods.each do |method_name|
      meth = method_name.to_sym
      callable = new_object.method( meth )
      begin
        context.instance_eval do
          define_method meth do |*args|

            callable.call( *args )
          end
        end
      rescue TypeError
      end
    end

    self
  end
end

class String
  include Abominate
  attr_writer :i_know_this_is_an_abomination
end

i = "hello world"
# => "hello world"

i.i_know_this_is_an_abomination = true

i.replace_object 100

i
# => 100

i.class
# => Fixnum