class SiteController

def response_cache_director(page)
  klass_name = "TrustyCms::#{page.class}ResponseCacheDirector"
  begin
    klass = klass_name.constantize
  rescue NameError, LoadError
    director_klass = "TrustyCms::PageResponseCacheDirector"
    eval(%Q{class #{klass_name} < #{director_klass}; end}, TOPLEVEL_BINDING)
    klass = director_klass.constantize
  end
  klass.new(page, self)
end