app.rb

# when handling a request on rack, thread_locals[:request] is set

module FrameworkStuff
  def request
    thread_locals[:request]
  end
end

auth.rb

class Auth
  extend FrameworkStuff
  include FrameworkStuff

  route '/signup/', :signup
  route '/logout/', :logout

  def signup
     if request.post?
        # process params
        redirect '/home' if validated
     end

     render 'login.haml' # if it is a get or didn't validate you render the login firm
  end

  # ...
end

site.rb

class Site
  extend FrameworkStuff
  include FrameworkStuff

  route '/', :home
  route '/some_subsection/', SomeSubsectionClass # passes this to a SomeSubsectionClass instance

  def home
     render 'home.haml'
  end
end

some_subsection.rb

class SomeSubsectionClass
  extend FrameworkStuff
  include FrameworkStuff

  route '/', :list
  route '/new/', :new

  def list
    objects = Model.all

    render 'list.haml', objects: objects
  end

  def new
    if request.post?
       # handle request
       redirect :list if validated?
    end

    renter 'blah.haml'
  end
end