James A. Crippen wrote:
>
> I have heard that only CMUCL appears to have such a function.
>
>
> Which is fine, because although EXT:FINALIZE is really useful, it
> doesn't work in all cases for me, so I'm just going to have to write
> C-like code to track when and where to free alien objects... Bleah.
MCL has that functionality, though it calls it "termination".
(defun foo-dispose (o)
;; Free the underlying resources
...)
(ccl:terminate-when-unreachable foo-obj #'foo-dispose)
MCL's implementation is pretty slick. It passes the object that is
eligible for termination to the termination function, for one thing,
and the termination function can store away a reference to the object,
which will then prevent the object from being GCed.
You can also call ccl:cancel-terminate-when-unreachable to stop
termination for an object.
It's really handy in the right situation, for sure.
(It looks like it's in OpenMCL, too. ccl/level-1/l1-stack-groups.lisp
has the code and a description of the API.)
John Wiseman
