From: Dave Burt <dave@...>
Date: 2005-09-29T21:36:44+09:00
Subject: Re: Concerning persistency techniques

Christophe Poucet:
>  The other remark I had was more of a question.  I have an object
> manager that tracks a whole set of objects (each with their own unique
> id).  This object manager is able to save and load (currently to YAML,
> but that is to be changed soon).  However one problem is that that all
> the class-types that could be saved have to be known by this object
> manager.  This results into the following code:
>
>    <snip code>
>
>  Does anyone have any suggestions on how to tackle this problem
> differently?

The following, taken from Ruby's docs, "implements a perverse kind of 
autoload facility" which may nevertheless solve a large part of your 
problem. The part that it won't solve may be solved by the addition of a 
lookup table mapping class names to their respective require paths.

def Object.const_missing(name)
  @looked_for ||= {}
  str_name = name.to_s
  raise "Class not found: #{name}" if @looked_for[str_name]
  @looked_for[str_name] = 1
  file = str_name.downcase
  require file
  klass = const_get(name)
  return klass if klass
  raise "Class not found: #{name}"
end

Cheers,
Dave