class Roda::RodaPlugins::Render::TemplateMtimeWrapper

def render(*args, &block)

changed, rebuild the template file, then call render on it.
If the template file exists and the modification time has 
def render(*args, &block)
  res = nil
  modified = false
  if_modified do
    res = @template.render(*args, &block)
    modified = true
  end
  modified ? res : @template.render(*args, &block)
end