I read these paragraphs over and over again ;) Maybe I just need someone
to explain it to me in different words.
So to apply these to my case:
- `ResolveBinding` is an *"abstract operation"* so it returns a
completion record, whose value is a *"Reference"*, even though
completion records are only supposed to have language values as value
(6.2.2) (this still confuses me)
- As per your quote, `Return ?ResolveBinding(...)` simply returns that
completion record.
- In `Let exprRef be the result of evaluating Expression`, `exprRef` is
a Reference, the completion record obtained by *"evaluating Expression"*
was implicitly unwrapped, according to 6.2.2.2: *"Any reference to a
Completion Record value that is in a context that does not explicitly
require a complete Completion Record value is equivalent to an explicit
reference to the `[[Value]] field of the Completion Record value unless
the Completion Record is an abrupt completion."`
Am I right so far?
Then, does the sentence
The algorithms of this specification often implicitly return Completion
Records whose `[[Type]]` is `normal`.
mean that
1. Algorithms may or may not return a completion record (i.e. some do
and some don't).
2. Algorithms *always* return a completion record, but it's not always
*explicitly* stated in the algorithm.
Felix
On 2016-09-23 03:32, Bergi wrote:
Felix Kling wrote:
I need some clarification around completion records.
You'll want to have a look at the algorithmic conventions
(http://www.ecma-international.org/ecma-262/7.0/#sec-algorithm-conventions)
and the implicit coercion of completion values
(http://www.ecma-international.org/ecma-262/7.0/#sec-implicit-completion-values):
| Calls to abstract operations return Completion Records.
| The algorithms of this specification often implicitly return
| Completion Records whose [[Type]] is normal. Unless it is otherwise
| obvious from the context, an algorithm statement that returns a value
| that is not a Completion Record, such as:
| > Return "Infinity".
| means the same thing as:
| > Return NormalCompletion("Infinity").
|
| However, if the value expression of a “return” statement is a
| Completion Record construction literal, the resulting Completion
| Record is returned. If the value expression is a call to an abstract
| operation, the “return” statement simply returns the Completion
| Record produced by the abstract operation.
Yes, it's a bit sloppy, but makes the spec much more readable. It's
already technical enough, so this does formally apply some common
sense :-)
kind regards,
Bergi
_______________________________________________
es-discuss mailing list
[email protected]
https://mail.mozilla.org/listinfo/es-discuss
_______________________________________________
es-discuss mailing list
[email protected]
https://mail.mozilla.org/listinfo/es-discuss
