On 1/9/13 12:13 PM, David Bruant wrote:
There is some data associated with the object. Whether it's a (private) property or a map entry is an implementation detail
...
Choosing symbols or a weakmap would make a huge difference in how proxy replacement would react to DOM algorithms.
Then it's not an implementation detail, now is it? I'm having a hard time understanding how you can reconcile those two sentences.
If the DOM in terms of accessing private properties, then proxies can replace DOM objects transparently. Their "unknownPrivateSymbol" trap will be called [2] and if they don't throw, the access to the private property will be transparently forwarded to the target without the private symbol ever leaking (it actually wouldn't need to exist in implementations). That actually could work...
I'm not sure I see how yet, but I'm not as familiar with proxies as you are. I assume the link above was actually [1]? I'm having a hard time making sense of it, largely due to missing context, I think.
What happens if unknownPrivateSymbol throws? Would internal DOM algorithms like the serialization algorithm invoke unknownPrivateSymbol? If so, would unknownPrivateSymbol be allowed to modify the DOM tree?
That would be representing private state with private symbols properties.
OK, see above.
Dom.js started and is developed in a world where no engines has implemented symbols.
It started in a world with no WeakMap or Map either.
Also, last I checked it adds non-standard convieniences [2] and _properties for "private" state [3][4]. Am I looking at the wrong version?
I believe it adds those on the target object but the thing it hands out to script is actually a proxy for that object.
I'm not sure how it handles "expando" property sets that collide with its _properties, though. But again, it was developed in a world without WeakMap/Map.
Yet, assuming the private symbol idea would be the way to go, there is still a need for specs to define private state in terms of private symbols before implementations can start, no?
Indeed.
implementations would be non-interoperable only in how many times the unknownPrivateSymbol trap is called which I don't think is really a big deal.
Whether it's a big deal depends on when it's called and what it can do. If it can have side-effects, non-interop in how many times it's called is a big deal to me.
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