From: Austin Ziegler <halostatue@...>
Date: 2005-09-06T11:28:03+09:00
Subject: Efficient Object Reconstruction?

I have a problem, and it's been bugging me for a while, so I thought
that I'd ask people that know a lot more about the internals of Ruby
than I do.

In PDF::Writer, I have a complex object graph. Its complexity is
mostly caused by the fact that all objects must know their parent
object. Maybe something like:

  foo#35
    bar#36 (@parent = foo#35, ...)
    baz#37 (@parent = foo#35, ...)

When this graph gets roundtripped through Marshal, I might have:

  foo#38
    bar#39 (@parent = foo#35, ...)
    baz#40 (@parent = foo#35, ...)

This means that there are now "odd" copies of at least the parent
(foo#35) around. This is something that *does* happen when
Transaction::Simple is called. Now, if I then add something else:

  foo#38
    bar#39 (@parent = foo#35, ...)
    baz#40 (@parent = foo#35, ...)
    bom#41 (@parent = foo#38, ...)

Obviously, this not only gets silly after a while, but it gets pretty
inefficient.

I want to fix Transaction::Simple so that the object graph is
*properly* reconstructed. That is, if I Marshal.dump the foo with
object ID 35, I don't mind if it's reconstituted as #38, but I want
"old" references to #35 reconstructed as references to #38.

How can I do that? Preferably, how can I do that without crawling the
object graph -- which would be extremely inefficient?

-austin
-- 
Austin Ziegler * halostatue@gmail.com
               * Alternate: austin@halostatue.ca