Having java-like weak references would indeed solve many problems and
would let us build our own collections.
On 21/03/2017 08:34, T.J. Crowder wrote:
What are your use cases for it?
Rather than tying it to being a `Map`, I'd prefer to see something
like Java's [`WeakReference`][1]: You could store the
`WeakReference`s in a `Map` if you wanted strongly-referenced keys
with weakly-referenced values.
-- T.J. Crowder
[1]:
http://docs.oracle.com/javase/8/docs/api/java/lang/ref/WeakReference.html
On Tue, Mar 21, 2017 at 6:15 AM, /#!/JoePea <j...@trusktr.io
<mailto:j...@trusktr.io>> wrote:
Hey all,
I'd like to have something like a WeakMap where the keys can be
primitives and the values are weakly-held Objects, so if there are
no more references to any of the Object values that the entry gets
removed from the map.
For example, it might look like this:
```
{
["foo"] => SomeObject,
["
bar
"] =>
OtherObject
,
}
```
where if there are no more references to `OtherObject`, then
`['bar'] => OtherObject` is removed from the map.
Usage would be very similar to WeakMap, like
```
let m = new ReversedWeakMap
m.add('foo', SomeObject)
m.add('
bar
',
OtherObject
)
console.log(m.get('bar')) // OtherObject
... time passes, no more references to OtherObject, OtherObject is
collected ...
console.log(m.get('bar')) // undefined
```
I thought of using WeakMap values as keys, and vice versa, but it
seems to be impossible.
I guess maybe it is difficult to add this natively because it
would mean that GC needs to be completely deterministic as far as
JS programs go. For example:
```js
let m = new ReversedWeakMap
function main() {
m.set('foo', {})
console.log(m.get('foo')) // {}
}()
main()
// GC would have to be guaranteed to have happened at this point.
console.log(m.get('foo')) // undefined
```
*/#/!//*JoePea
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