The Forwardable module provides delegation of specified methods to a designated object, using the methods def_delegator and def_delegators.

For example, say you have a class RecordCollection which contains an array @records. You could provide the lookup method record_number(), which simply calls #[] on the @records array, like this:

  class RecordCollection
    extend Forwardable
    def_delegator :@records, :[], :record_number
  end

Further, if you wish to provide the methods size, #<<, and map, all of which delegate to @records, this is how you can do it:

  class RecordCollection
    # extend Forwardable, but we did that above
    def_delegators :@records, :size, :<<, :map
  end
  f = Foo.new
  f.printf ...
  f.gets
  f.content_at(1)

Also see the example at forwardable.rb.