On Sep 12, 2013, at 12:40 PM, Jason Orendorff <jason.orendo...@gmail.com> wrote:
> Just as a worked example, answering Oliver's question about default
> expressions took me the better part of an hour.
>
> The default-expression h() in code like
>
> function f(x=h(), y) {
> function h() { ... }
> }
>
> is evaluated in the scope of f, as I expected, so {x, h, y} are all in
> scope there.
>
> But I was surprised by the timing; h() is evaluated
> (a) before y is populated with the actual argument value;
> (b) before the arguments object is fully initialized.
>
> That last surprise seems really unfortunate, since the expression can
> access the arguments object, observing it before and after
> CompleteMapped/StrictArgumentsObject, or even cause those to fail. Can
> we change that?
>From talking to SpiderMonkey folk it sounds like SM nukes the |arguments|
>identifier entirely if you use any of the new parameter logic (deconstruction,
>defaults, or rest params). I would be happy with that.
The spec (from my understanding) says that we can't declare a parameter named
arguments but does limit reads of it. Also that doesn't limit declarations of
a local named arguments
--Oliver
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