Using Rack::Builder without eval-ing block in another context.

m_app.rb

require 'rack'
require 'forwardable'

class MyApp
  extend Forwardable
  def_delegators :@builder, :use, :map, :run, :call
  
  def initialize
    @builder = Rack::Builder.new

    map '/route1' do
      run SampleApp.new
    end

    map '/route2' do
      run SampleApp.new
    end

  end
end