Use Rails (ActiveSupport) delegation class in plain ruby

# Gemfile
source "https://rubygems.org"
gem 'active_support'

require 'active_support/core_ext/module/delegation'

class Foo
  delegate :call, to: :other

  def other
    ->(){ 'foo' }
  end
end

Foo.new.call
# => 'foo'

source: http://guides.rubyonrails.org/active_support_core_extensions.html#method-delegation`

github: https://github.com/equivalent/scrapbook2/blob/master/archive/mini-blogs/2015-04-23-use-rails-delegate-lib-only.md