From: Claus Spitzer <DocBoobenstein@...>
Date: 2004-05-07T01:43:15+09:00
Subject: Re: model for my problem (network simulator)

8< snip

> > > Just one little thing (chicken-egg problem): the links should know
> about
> > > the 2 ending nodes, and nodes must know about in/outgoing links. So
> how
> > > to easily administrate it?
> >
> > That's easy in ruby, as ruby is garbage-collected, so it can clean up
> > circular references by itself.  Thus, you can add a list of both the in
> and
> > outgoing links to each nodes.
> 
> IMHO the question was rather how to manage those references so that they
> are always in sync.  That would be the typical problem with bi directional
> references in OO languages.  Typically you manually have to write code for
> that (unless you find a library that does it gracefully) but if done
> properly you need to do it only once and can then reuse that code.
> 
>     robert
> 
> 

Probably (and that is _only_ probably, as in "this is how I have seen
it implemented in other instances by very smart professors") you'll
want do do something along the lines of:

* both the nodes and links have a list of what is attached to them. 
* both are observers and observables
* a change in the node notifies the link, and vice-versa

Otherwise, if for example only the links initiates the change, then
you can make them be the observables and the nodes just the observers.
Cheers!
  -CWS