Question

So I’m thinking of using method missing to construct several datetime methods that I need for the large number of datetimes that I have to manage.

I am basing this method on Ryan Bates virtual attributes and believe I have this metaprogramming challenge down (my 1st one!) except for one little snafu that I haven’t yet solved…

For this part of my method I am getting an error concerning the = which is supposed to be unexpected…

    define_method(save_method) do
      self.send(attribute) = Chronic.parse(args[0], context: :past) if instance_variable_get("@#{method_name}").present?
    end

The method is supposed to be expecting a ) instead…but I haven’t been able to figure it out.

def method_missing(method_name, *args)
  if method_name.to_s.match(/^chronic_(\w+)/)

      save_method     = "save_#{method_name}"
      validate_method = "check_#{method_name}"
      attribute = method_name.to_s.gsub(/^chronic_/, '').to_sym

      self.class.class_eval do
        attr_accessible method_name.to_sym
        attr_writer     method_name.to_sym
        validate        validate_method.to_sym
        before_save     save_method.to_sym

        define_method(save_method) do
          self.send(attribute) = Chronic.parse(args[0], context: :past) if instance_variable_get("@#{method_name}").present?
        end

        define_method(validate_method) do
          if instance_variable_get("@#{method_name}").present? && Chronic.parse(args[0], context: :past).nil?
            errors.add :released_at_text, "cannot be parsed"
          end
        end

        define_method(method_name) do
          instance_variable_get("@#{method_name}") || attribute
        end

      end
      puts attribute
      send(method_name)
    else
      super
    end
  end

Answer 1

define_method(save_method) do
  self.send("#{attribute}=", Chronic.parse(args[0], context: :past)) if instance_variables.include?("@#{method_name}")
end

“=” is a part of method of setter method name so you have to send("#{attribute}=", value)