Save Object.observe()! (please) + make WeakMap/WeakSet observable.

[Romuald Quantin]

Someone made an experiment with the Mozilla “getWeakReference” apparently.

https://gist.github.com/Benvie/7123690
https://developer.mozilla.org/en-US/docs/Mozilla/Tech/XPCOM/Language_Bindings/Components.utils.getWeakReference

I had this as granted with other languages, I still don’t understand why
has this not been enabled by default in javascript.

On 4 November 2015 at 22:54, Coroutines <coroutines at gmail.com> wrote:

> On Wed, Nov 4, 2015 at 2:36 PM, Rick Waldron <waldron.rick at gmail.com>
> wrote:
>
> > On Wed, Nov 4, 2015 at 8:16 AM Coroutines <coroutines at gmail.com> wrote:
>
> >> obj[Symbol.weakValues] = true;
> >> obj[Symbol.weakProperties] = true;
>
> > 2. For security purposes, only code that has been explicitly given
> access to
> > _both_ the weakmap and a key may gain access to the value stored within
> the
> > weakmap. This is why there is no enumeration—if there were, then any code
> > that could access the weakmap could then also access all of the keys and
> > values. If that's a desirable trait, then just use a Map.
> >
> > These things cannot be done with Proxy, because anything that Proxy does
> > will inevitably be a strongly held reference.
>
> Well, you explained the mystery behind why WeakMap can't be iterated
> over - but I was saying I would combine Proxy with a theoretical
> Symbol for marking keys and/or values as weakly-referenced to create
> WeakSet and WeakMap (if I wanted).  I think I just prefer Lua in this
> area:
>
>   local tmp = setmetatable({ 'a', 'b', 'c' }, { __mode = 'v' })
>
>   for k, v in ipairs(tmp) do
>     print(k, v)
>   end
>
> 'a', 'b', and 'c' are weakly-referenced and can be iterated over, will
> be marked by the next GC step, and will not survive the next GC
> collection cycle.  I wish JS let me create weak references as simply:
>
>   var tmp = [ 'a', 'b', 'c' ]
>
>   tmp[Symbol.weakValues] = true;
>
> This is what I was saying :>  I understand that you need both a
> reference to the WeakMap and the object you're using as a "weak key"
> but I think it could be iterable if the weak references have not been
> broken yet - if the objects in that WeakMap have not been collected
> yet.  I would not want "permanently" strong references with a Map.
>



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