On Jul 15, 2013, at 6:49 AM, Jeremy Martin wrote: > > In some (most?) cases, but not all. There's already a consensus that the > garbage collection semantics of WeakMaps aren't always appropriate [2]. By > parameterizing the Symbol constructor, developers can create custom map/set > types without the overhead of a "Symbol Factory" (as previously suggested by > Allen). I believe this would be a useful building block for interesting and > innovative custom types. > > [1]: https://en.wikipedia.org/wiki/Injective_function#Definition > [2]: http://wiki.ecmascript.org/doku.php?id=harmony:simple_maps_and_sets
An implementation of your proposal is going to have to have to internally use some wort of weak-keyed table, in practice an implementation would probably use the same GC mechanisms that are there to support WeakMap. So, I doubt there would be much performance difference between a built-in and a roll-your-own implementation. Allen
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