POS

[BRIAN SPILSBURY]

> BRIAN SPILSBURY wrote:
> > I think that weak-references will solve your issues in pretty much all
> > cases with a little design. A weak reference being a refence that does not
> > protect from garbage collection, and will be redirected to nil if the
> > object its referencing gets collected.
> 
> As soon as you introduce this concept you are destroying the abstraction
> of infinite memory. In other words, the "transparent object oriented
> file store" is no longer transparent. Applications must make value
> judgements of what must hang around forever and what is expendable.
> That's what I was advocating.
>  
>  Paul Prescod

It is transparent in that there is no difference to anything except for
the garbage collector, and that you can't guarantee that a weak-reference
won't suddenly point to nil at any given time. The illusion of
infinite memory imho isn't terribly useful.

the "transparent object oriented file store" is transparent in the sense
that it is not distinguishable, it is transparent in that the entire
system is persistent, with the added tools that are useful for the garbage
collection of complex systems.

Inside this its relatively straightforward to build a transactional store,
but do you really want to go back to the land of 'malloc/free'? Or would
a (push (weak x) index) be more lispish with null values flushed from the
index periodically?

Also _just_ having a transactional POS kills persistence of execution 
entirely, which is something definately worth considering.

Brian