Temporary Execution Context With Included Modules

I needed to extend "self" with a module but only wanted the included methods to stick around "temporarily". After a lot of futile attempts with binding, callcc, eval, etc... I found it was as simple as "self.dup.instance_eval { ... } ":


def foo
  'bar'
end

module M
  def foo
    'baz'
  end
end

puts "should be 'bar': #{foo}"

self.dup.instance_eval do
  extend(M)
  puts "should be 'baz': #{foo}"
end

puts "should be 'bar': #{foo}"