From: Logan Capaldo <logancapaldo@...>
Date: 2006-09-05T07:10:28+09:00
Subject: Re: How to store/load persistent data?


On Sep 4, 2006, at 1:30 PM, Josef Wolf wrote:

> Hello!
>
> In my previous life (in perl-world) I was used to store persistent  
> data
> with Data::Dumper and load it back with "require '/path/to/file'".
>
> Now I'm learing ruby and started my first toy-project.  I must  
> admit that
> I am not very familiar with OO techniques.
>
> AFAICS, the ruby way to store persistent data is YAML.  Saving an  
> object
> with YAML.dump() works like a charm.  But I have trouble to read them
> back with YAML.load().  For some reason, the initialize() method of  
> the
> loaded object doesn't get called.  I don't understand how an object  
> can
> properly spring in existance without the initialize method?

Well the general purpose of initialize is to set up some state /  
instance variables. That's exactly what the serialized form of the  
object keeps track of anyway.

>   For example,
> I allocate a TkCanvas in the initialize() method.  Such an object  
> can not
> be loaded back properly, IMHO.
>

Some things aren't serializable in a sane way, that's just a fact of  
life.

> I have one more problem with such an object: There's no  
> destructor.  Should
> such an object get out of scope, how do I make sure the allocated  
> canvas
> is destroyed properly?
>
The garbage collector makes sure that the memory used by objects that  
go out of scope is reclaimed.

> I'm sorry if this is a stupid question, but I am new to both, ruby  
> and OO.
> Please can somebody give an explanation how such an object is  
> handled in
> the ruby-world?
>