actually, in my working copy of the spec, CheckIterable has already been
updated to look like:
1. If obj is undefined or null, then return undefined.
2. Return GetV(obj, @@iterator).
where GetV is similar to Get but it boxes non-object values before doing the
property lookup
When you find issues like this, the best thing to do is to simply submit a bug
ticket at: bugs.emcascript.org
Allen
On Dec 22, 2014, at 4:32 PM, Gary Guo wrote:
> Actually I propose a change in texts in the specification.
>
> >CheckIterable ( obj )
> >1. If obj is `undefined` or `null`, then return `undefined`.
> >2. If type(obj) is Object, then return Get(obj, @@iterator).
> >3. Let box be ToObject(obj).
> >4. ReturnIfAbrupt(box).
> >5. Return the result of calling the [[Get]] internal method of box passing
> >@@iterator and obj as the arguments.
>
> This is way more too complex. We know that there are three situation:
> 1. obj is `undefined` or `null`
> 2. obj is of a primitive type
> 3. obj is an object
>
> In 1, we don't care if it returns undefined or throw a TypeError. In ES6
> spec, there are two uses of the undefined returned. One of them passes it as
> F to Call, the other passes it to ToObject. Both of them will result in
> TypeError. So we can just let this step throw TypeError instead of return
> `undefined`.
>
> I suggest we can a little bit combine these steps:
>
> >CheckIterable (obj)
> >1. Let box be ToObject(obj).
> >2. ReturnIfAbrupt(box).
> >3. Return the result of calling the [[Get]] internal method of box passing
> >@@iterator and obj as the arguments.
>
> If obj is `undefined` or `null`, the first step will fail and throw
> TypeError. If obj is primitive, it's boxed. If obj is an object, it is no-op
> in ToObject.
>
>
>
>
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