> This looks like the situation addressed in Java by a variation of
> weak references called "soft references".  They are like weak refs
> in that they don't prevent garbage collection but the collector will
> not clear them unless there is memory pressure.  We use them for
> the kind of caching you describe.  I don't know enough about the
> Squeak VM to determine their feasibility in Squeak.  They are
> very handy in Java.

I would appreciate an explanation of their utility.  I'm sure I'm simply being dull, but I don't understand why this would be necessary or helpful.