callable.rb

module WebAction
  def self.inherited(subclass)
    super
    subclass.prepend Callable
  end

  module Callable
    # Set up instance method that accepts env, request, response
    # and calls method inside Action without any arguments.
    def call(env, request, response)
      @env = env
      @_request = request
      @_response = response
      super()
    end
  end
end

class SomeAction
  include WebAction

  def call
    # Look mah, no arguments
  end
end