On Jan 14, 2013, at 9:32 PM, Dmitry Soshnikov wrote:
> Hello,
>
> Don't know whether it was mentioned/asked before (sorry if so), but just a
> note: probably it makes more sense making the target argument as optional and
> the second one in the Proxy constructor's API.
>
> Proxy(handler[, target]):
>
> 1. If target is undefined, let the target be new Object();
> ...
>
> In this case we'll cover (probably the most used) use-case of direct-proxies:
>
> var p = new Proxy({
> get: function(target, name, value) {
> ...
> }
> });
Although... Actually, never-mind, I just looked at it again, and it looks a bit
weird having some first argument "target" w/o actually specifying the one at
creation. So yeah, explicit target makes sense. I just wanted to exclude these
use-cases:
var p = new Proxy({}, handler);
where this use-less empty "{}" will be to many in proxies' code.
P.S.: I know it's not gonna happen, but in an "imaginary" world:
Anyways, if the explicit target, then it would be good refer it as `this` value
instead of explicit parameter. But in this case we cannot get reference to the
handler object (currently `this` refers to the handler object). But. Since
proxies provide some internal meta-level API handling, we can refer the
handler's method as private symbols instead. E.g.:
var p = new Proxy({
@get: function (name, value) {
if (this.@getOwnPropertyDescriptor(...)) {
this[name] = value;
}
}
});
`this` refers to the target, but this.@getOwnPropertyDescriptor(...) to the
function of the handler object. But this is only at implementation level, from
the end-level user's perspective, it looks like `this` is the target and
`this.@getOwnPropertyDescriptor(...)` is the internal method hook on exactly
the same target.
In this case, optional target becomes completely implicit and can be treated as
just a "traceable" object.
This doesn't reflect some invariants as `p === this`, if p is the proxy and
`this` is the target (and this is why p.name = 10; triggers the handler and
this.name = 10; inside the handler function does not), so, just thinking saying.
Dmitry
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