On Wed, Nov 4, 2015 at 2:36 PM, Rick Waldron <[email protected]> wrote:
> On Wed, Nov 4, 2015 at 8:16 AM Coroutines <[email protected]> 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. _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
