Questions about GetValue() in Runtime Semantics Evaluation of the with Statement in 13.11.7

[sakura90]

Hi,

Some questions about the following steps in 13.11.7.

13.11.7 Runtime Semantics: Evaluation
WithStatement : with ( Expression ) Statement

1. Let val be the result of evaluating Expression.
2. Let obj be ? ToObject(? GetValue(val)).
3. Let oldEnv be the running execution context's LexicalEnvironment.
4. Let newEnv be NewObjectEnvironment(obj, oldEnv).
5. Set the withEnvironment flag of newEnv's EnvironmentRecord to true.
6. Set the running execution context's LexicalEnvironment to newEnv.
7. Let C be the result of evaluating Statement.
8. Set the running execution context's LexicalEnvironment to oldEnv.
9. Return Completion(UpdateEmpty(C, undefined)).

I guess I understand most of what the evaluation is about. The object of Expression is binded in a new environment, and Statement is evaluated in the new environment.

I am not very sure about the details of some of the steps and I have some questions below.

In step 1, what is the specification type of val?
In step 2, what is the reference that calls GetValue(val)?
If the specification type of val is reference, in step 3 in 6.2.4.8 GetValue(V), what does the base value component of V store? And in step 5b, what does the referenced name component of V store?

If an example is going to help explain, please use the following example or any other examples for the explanation.

var a, x, y;
var r = 10;

with (Math) {
a = PI * r * r;
x = r * cos(PI);
y = r * sin(PI / 2);
}

The questions may be asking too many details of 13.11.7, and it may not be what the way is to understand 13.11.7. If the steps of 13.11.7 are supposed to be conveying the rough steps of how evaluation is done, and my understanding does not have to cover the details, please feel free to let me know.

Thanks,
Patrick

[devsnek]

in your example Expression is an Identifier which gets evaluated into a Reference whose base component is the global environment record, and the referenced name is "Math"

[devsnek]

in your example Expression is an Identifier which gets evaluated into a Reference whose base component is the global environment record, and the referenced name is "Math"

[sakura90]

Thank you very much. I have got a better understanding.

[sakura90]

Thank you very much. I have got a better understanding.