What you think you need: iterable WeakMap What you really need: WeakReference, PhantomReference.
Personally I think we need built-in class "GarbageCollectorObserver" that emit events for each observed collected object (uniquely identified by strongly-held symbols), it will solve most of problems associated with binding models and views. On Wed, Jul 13, 2016 at 2:13 PM, Michael Kriegel < [email protected]> wrote: > Hi everyone, > > not sure, whether this is the right place for discussing a feature request > - and how to find out, whether this was already proposed/discussed before > and with which result... My google search did not bring up anything about > it. > > On my opinion it should be made possible to iterate over all elements in a > WeakSet & WeakMap. I already found many cases, in which I'd like to have > used the neat feature of "garbage collect the object, if it is not referred > to by others anymore", but with the necessity to know, which objects are in > the set (not only, if a given object is). An example: > > Registering callbacks to objects: > > class Foo { > onBla(Handler) { > this.BlaSuperWeakMap.push(Handler); > } > > someOtherMethod() { > for (let X in this.BlaSuperWeakMap) { > X(); > } > } > > constructor() { > this.BlaSuperWeakMap = new SuperWeakMap(); > } > } > > const MyFoo = new Foo(); > { > let MyHandler1 = function(){ > console.log('MyHandler1 called'); > }; > MyFoo.onBla(MyHandler1); > console.log('Invokation1:'); > MyFoo.someOtherMethod(); > } > let MyHandler2 = function(){ > console.log('MyHandler2 called'); > }; > MyFoo.onBla(MyHandler2); > MyFoo.onBla(function(){ > console.log('MyHandler3 called'); > }); > console.log('Invokation2:'); > MyFoo.someOtherMethod(); > MyHandler2 = undefined; > console.log('Invokation3:'); > MyFoo.someOtherMethod(); > > Expected result: > Invokation1: > MyHandler1 called > Invokation2: > MyHandler2 called > Invokation3: > > Basically the example is: Invoke the callback of all objects which still > "exist" (in the meaning of having "non-weak" references towards them). > > I know this may have some caveats. It would be necessary to check the > reference count of the object in the SuperWeakSet, because the object may > have no "non-weak" references left but still was not yet garbage collected. > I do not know, whether current ECMAScript-Implementations and their garbage > collecting solutions could handle this easily - basically it is the same > decision, which the garbage collector would make: If an object can be > disposed, because it has no non-Weak references pointing to it, the object > is by definition not in the WeakSet anymore. And implementations could in > that case even give a hint to the garbage collector, which may improve > performance of applications, which use the SuperWeakSet alot. > > Greetings, Michael > > > > > > > > > > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss >
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