[slime-devel] weak hash tables and presentation

[Geo Carncross]

On Feb 4, 2008 5:53 PM, Lynn Quam <quam at ai.sri.com> wrote:
> I word of warning:
>
>    Weak hashtables (and weak pointers in general) have significant
>    implications for the garbage collector.  Even after many attempts
>    to fix the CMUCL garbage collector, the use of weak hashtables
>    still causes problems.

ECL uses the bohem collector presently. Making weak hashtables
basically involves adding a GC_register_disappearing_link() wipe out
the cell when it finalizes and store a disguised pointer (say, xor ~0
or something) instead of the original pointer. If ECL ever got a
precise collector (again) this would be a different story.