On Dec 21, 2010, at 4:01 PM, Oliver Hunt wrote:
> Just giving my feedback to this (so it's recorded somewhere other than my
> head).
>
> I find the apparent necessity of conflating syntax and semantics irksome, i'd
> much rather that there be two distinct discussions one of syntax and the
> other for semantics of soft-fields, private names, gremlins, etc (or whatever
> this general concept ends up being called)
>
> That said I don't really like the private names syntax, mostly for reasons
> others have bought up already, but one case I don't recall seeing is
> something that I think will lead to surprise on the part of developers. Say
> i have a piece of code:
>
> function MyAwesomeThing() {
> ....
> }
>
> MyAwesomeThing.prototype.myCoolFunction = function() {
> if (!this._myCachedHotness)
> this._myCachedHotness = doExpensiveThing(this)
> return this._myCachedHotness;
> }
>
> I see this nifty private names feature, and say "cool! now i can make my
> cache super secret!" and do:
>
> MyAwesomeThing.prototype.myCoolFunction = function() {
> private cachedHotness;
> if (!this.cachedHotness)
> this.cachedHotness = doExpensiveThing(this)
> return this.cachedHotness;
> }
>
> I would _expect_ this to work. That's what the syntax makes me think. But
> it won't work because 'cachedHotness' is going to be different on every call
> (at least to my reading).
Why does your expectation differ here compared to the following:
MyAwesomeThing.prototype.myCoolFunction = function() {
var cachedHotness = gensym();
if (!this[cachedHotness])
this[cachedHotness] = doExpensiveThing(this)
return this[cachedHotness];
}
Is it because |private cachedHotness;| does not "look generative"?
> I am not trying to argue that making the above work is impossible -- you just
> need to use a few closures to get everything into the right place. But it is
> contrary to what I might expect or want.
>
> wrt. proxies, I still think that we should just allow all non-objects
> property names to transfer through uncoerced. It would solve the problem of
> communicating private names to a proxy and allow efficient array-like
> implementations.
You mean non-string property names, right?
But what is an array index, then? uint32 is not a type in the language. Would
proxy[3.14] really pass a double through?
Array elements are named by a weird uint32 index name, with consequences on
'length' (but only up to 2^32 - 1 for length). I don't think passing the
property name through uncoerced helps, unless you assume a normalizing layer
above all name-based operations that specializes to index-names per Array's
uint32 magic weirdness.
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