Not sure I've got your idea right but I think the main point of WeakAnything is to forget about GC and have them **not** observable "at all costs" .... unless I've misunderstood the intent itself, Object.observe as it has been proposed wouldn't help much anyway.
Regards On Mon, Nov 2, 2015 at 10:34 PM, Coroutines <[email protected]> wrote: > I was referred to es-discuss after filing a feature request here to > support observing WeakMaps and WeakSets. ( > https://bugzilla.mozilla.org/show_bug.cgi?id=1206584 ) > > I was linked this message: > https://mail.mozilla.org/pipermail/es-discuss/2015-November/044684.html > > Please save Object.observe(). > > When I read that above posting it sounds like O.o() is to be removed > because it has not been popularly used. It is proposed for ES7 - it's > not even part of an accepted standard yet. I think it's strange to > remove something because it's not used much... because it's > experimental. Who would depend on something non-standard? Sure > there's a polyfill but it polls an object for changes with timers - > this sounds ridiculously inefficient. If it doesn't get accepted > there will be no way to watch changes as they happen, instead of after > the fact. > > I come from Lua. In Lua we make proxy objects with metamethods. You > create an empty table/object and define a metatable with a __index and > __newindex to catch accesses and changes when a key/property doesn't > exist. I would primarily use this in sandboxes where I wanted to > track the exact series of operations a user was performing to modify > their environment (the one I'd stuck them in). The important part to > remember is that I didn't know what properties of which objects they > would be accessing. I couldn't just define a static list of getters > and setters and hope they make use of my limited, catching interface. > I think Object.observe() is very important for situations where you > want to watch all changes, because you don't know which properties > will be used. > > I have a further proposal: I wish it were possible to watch changes > on WeakMaps and WeakSets. > > In Lua you can have weak references by setting the __mode = 'kv' (k > for key, v for value) in the object's metatable. The only way I could > get weak references in JS was with WeakMaps and WeakSets. Lua also > lets you set a __gc in the metatable to handle when a pair is > collected by the GC. I wanted the ability to "see" when memoized > function calls are forgotten, but I can't do that with just > Object.observe() - as you can't observe a WeakSet or WeakMap. I'd > love for this to be possible. > > For debugging reasons it would be excellent to be able to watch when > things get collected (through weak references). Finalizers in general > would be nice. I mean in the sense that I want to do something > independent of the object being collected, not that I need to destroy > the object in a special way before collection. I feel like there's a > vague difference between finalizer and destructor. > > Please save Object.observe(), make WeakMap/WeakSet observable, and > save the whales too or something. > > Toodles ~ > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss >
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