Allows properly namespaced apps with "controllers" and models where they "should" be

sinatra_app_layout.rb

require 'sinatra/base'

module M1

  def self.apps
    @apps ||= {}
  end

  class A < Sinatra::Base

    def self.namespace(namespace)
      M1.apps[namespace] = self
    end

    not_found do
      "Sorry, not found"
    end

  end

  module M2

    class B < M1::A

      namespace '/B'

      class C < M2::B

        namespace '/B/C'

        class D < M2::B::C

          namespace '/B/C/D'

          get '/d' do
            'rendered M2::B::C::D at /B/C/D/d'
          end

        end

        get '/c' do
          'rendered M2::B::C  at /B/C/c'
        end

      end

      get '/b' do
        'rendered M2::B at /B/b'
      end

    end

  end

end

run M1.apps # if you run a hash, it sets up a map