From: Ryan Davis <ryand-ruby@...>
Date: 2012-09-13T08:51:19+09:00
Subject: Re: Marshaling classes


On Sep 12, 2012, at 16:13 , Damián M. González <lists@ruby-forum.com> wrote:

> Guys, how are you?
> I'm stuck thinking about how can I save the state of a class. I want to
> save the class variables of some classes. Do I have to require to
> metaprogramming for this? I mean: save those variables in an object,
> then dump it marshaling and then re-construct a class from that object
> when is loaded. I'll try to explain the situation in an example:

Two ways I can think of off of the top of my head:

1) use `maglev-ruby -Mpersistent` to run your code and you're done.

> class Dog
> @@quantity = 5
>   def self.change_quantity=(n)
>     @@quantity = n
>   end
>   def self.show_quantity
>     @@quantity
>   end
> end


2) Rename your methods to reflect good ruby (def self.quantitiy and def self.quantity=) and then make them persist your values. Change the getter to a lazy accessor that will read in the value from disk (or whatever) and change the setter to persist the change back out.

def self.quantity
  @@quantity ||= Marshal.load(...) # or whatever
end