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discard """
output: "true"
"""
import intsets
type
TMyObject = object
id: int
StrongObject = ref TMyObject
WeakObject = object
id: int
data: ptr TMyObject
var
gid: int # for id generation
valid = initIntSet()
proc finalizer(x: StrongObject) =
valid.excl(x.id)
proc create: StrongObject =
new(result, finalizer)
result.id = gid
valid.incl(gid)
inc gid
proc register(s: StrongObject): WeakObject =
result.data = cast[ptr TMyObject](s)
result.id = s.id
proc access(w: WeakObject): StrongObject =
## returns nil if the object doesn't exist anymore
if valid.contains(w.id):
result = cast[StrongObject](w.data)
proc main =
var s: seq[WeakObject]
newSeq(s, 10_000)
for i in 0 .. s.high:
s[i] = register(create())
# test that we have at least 80% unreachable weak objects by now:
when defined(gcMarkAndSweep):
GC_fullcollect()
var unreachable = 0
for i in 0 .. s.high:
if access(s[i]) == nil: inc unreachable
echo unreachable > 8_000
main()
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