Simple Rack setup where you can move your middleware and map config to another file

app.rb

App = lambda do |env|
  [
    200,
    { "Content-Type" => "text/plain" },
    [
      "Hello!\n",
      "self in config.ru is: #{RACK_BUILDER.to_s}\n",
      "@use = #{RACK_BUILDER.instance_variable_get(:@use)}\n",
      "@map = #{RACK_BUILDER.instance_variable_get(:@map)}\n",
    ]
  ]
end

config.ru

$LOAD_PATH.unshift('.')

# bind this instance to a constant
RACK_BUILDER = self
require 'app'
require 'routes'

routes.rb

RACK_BUILDER.instance_exec do
  # use, map and run are working here
  use Rack::Lock
  map '/subtest' do
    run App
  end
end

easy :) I like
Should make it easier for development at least