Honestly, because I was too rushed to try them before I had to leave
this morning. :D However, now that I have the chance, I've found that
Typed Racket doesn't support them. I can't add support using
`required/typed', because `Weak-Box' would have to be a polymorphic type.
Also, they don't seem to let go of procedure values. This one's value
doesn't ever turn to #f no matter how many times I collect garbage:
(define bx (make-weak-box (λ (_) 0)))
Thinking it might be because that lambda doesn't create a closure, I
tried this:
(define (make-box-thing v)
(make-weak-box (λ (_) v)))
(define bx (make-box-thing 4))
But this `bx' doesn't let go of its value, either. I can't help but
think I'm missing something really stupid, though.
Neil ⊥
On 12/01/2012 10:58 AM, Robby Findler wrote:
How about using a weak box instead?
Robby
On Sat, Dec 1, 2012 at 11:45 AM, Neil Toronto <neil.toro...@gmail.com> wrote:
I'm getting ready to push a change to math/array that fixes a memory leak.
I've devised a test that I think will determine whether an array's procedure
gets collected after the array is made strict, but I don't know whether it
works only by accident. Here it is:
(define: collected? : (Boxof Boolean) (box #f))
(define arr
(let ([proc (λ: ([js : Indexes]) 0)]) ; constant array
(register-finalizer proc (λ (proc) (set-box! collected? #t)))
(build-array #() proc)))
(array-strict! arr)
(collect-garbage)
(sleep 0) ; give finalizers a chance to run?
(check-true (unbox collected?))
This test passes for me now, but will fail if anyone else tries it. What
worries me is that (sleep 0) is apparently required, meaning that finalizers
aren't run immediately when garbage is collected.
How can I ensure that the finalizer for `proc' gets run before I test the
value of `collected?'?
Neil ⊥
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