From: mirian@... (Mirian Crzig Lennox)
Date: 2001-06-10T10:33:54+09:00
Subject: [ruby-talk:16378] Re: other ways to create class instance?

In article <3B22BD76.3E04270A@objectent.com>,
Samantha Atkins <samantha@objectent.com> wrote:
>Hi,
>
>I was fooling around with object persistence ideas in Ruby and
>came to a question I haven't found an answer to yet.  How can I
>create an instance of a class X without invoking X.new(...)? 
>What I need is to be able to create an instance with the right
>plumbing set up and hand set instance variables from data
>retrieved for the persistent form of the object.  So how would
>you do that?

Possibly the marshalling support in Ruby is what you're after.  It
allows you to specify a class method X._load() which loads an object
of class X from persistent store.  You can handle all of your custom
plumbing inside that method, which will however probably need to begin
with a call to X.new() to allocate the initial version of that object
to fiddle with.  You can also define a method _dump() on that object
to write it out to persistent store.

The Marshal module takes care of calling these hooks, and can also
write objects to persistent store by means of a default protocol for
classes which don't define _load() and dump().

Pages 272-274 of the Pickaxe book describe marshalling in Ruby.

--Mirian