module Rtml::Controller::CacheHelpers
  def expires_at(val = nil, &block)
    if val
      @expires_at = proc { val }
    else
      @expires_at = block if block_given?
    end

    if @expires_at
      @expires_at
    else
      if self.class.respond_to?(:expires_at)
        self.class.expires_at
      else
        nil
      end
    end
  end

  def self.included(base)
    base.send(:extend, self)
    base.instance_eval do
      hide_action :expires_at
    end
  end
end