From: jason@... (Jason Voegele)
Date: 2001-09-27T23:32:24+09:00
Subject: [ruby-talk:21772] Transparent Proxies

Hello all,

I'm trying to implement a persistent object store similar to an Object
Oriented Database.  One feature of this object store is on-demand
loading of objects, such that an object is only loaded from the
database when it is needed.

I've been thinking about the various ways to implement this but have
not come up with a satisfactory solution.  There was some time back a
discussion about the possibility of adding a "become" feature (ala
Smalltalk) to Ruby that would provide exactly what I need, but it
appears that there were many problems with "become" that prevent it
from being added to the language.  I know also that there is a
standard "delegate" package for Ruby, but there are other problems
with this, such as "delegate.class" won't return the right thing, and
seemingly severe performance problems noted in this post:

http://groups.google.com/groups?q=delegate&hl=en&group=comp.lang.ruby&rnum=4&selm=fWQS6.109749%24I5.25755148%40news1.rdc1.tn.home.com

What I'm looking for is a means of implementing a transparent proxy,
such that things like "proxy.class" work as expected and allows the
proxy to be replaced with the actual object when it becomes necessary,
and all of this without being "too" slow.  Any ideas?

C++ tends to do this by allowing pointers to "fault" and catching the
exception.  I don't think I can do this in Ruby, and I'm not sure that
I'd want to anyway.

Thanks,
Jason Voegele