On Wed, Sep 17, 2008 at 7:37 AM, Mike Shaver <[EMAIL PROTECTED]> wrote:
> On Wed, Sep 17, 2008 at 3:07 AM, Garrett Smith <[EMAIL PROTECTED]> wrote:
>> Instead, it would be more useful for all thrown objects to get a stack
>> property, unless the object already had one.
>
> This has been proposed before in Mozilla, but I and others objected
> because we don't believe that throwing an object should mutate it, and
> because it would cause primitives to be boxed by the property set (or
> have more just-so ad hoc logic that is hard to reason about).
>
While I appreciate the stack property, I disagree on that detail.
If a native object is thrown, and that object is not an Error, then
the either the developer threw it using throw or a Host object threw
it. Right?
If a thrown native object did not already have a stack, what is the
harm in adding one?
Now, if the thrown object already had a stack property then it might
be best to just leave that alone and not replace the value.
A thrown Host object should have a stack property, but doesn't have to
(a DOMException object, for example). calling [[CanPut]](o, "stack"),
prior to adding a stack would allow implementations to have the option
to add a helpful stack property.
throw Error("msg");
- resulting in a stack, or the hypothetically more efficient:-
throw "msg"
Throwing a Host object:
function makeNode(tag) {
try {
document.createElement(tag);
} catch(ex) {
alert(ex.stack);
}
}
// Should raise DOMException.
makeNode(':/');
Thoughts?
I can also write up the pseudo-code algorithm steps for review.
> I would be more amenable to have {Syntax,}Error.throwObject(obj)
> provide an Error with stack, and the provided obj as .data or some
> such.
A throwError method. Hmm. How would that work? I guess if the method
were generic, the properties |type| and |message| would not be
changed. Right?
I think |throw| would be easier to spot in source code than
|Error.throwObject|. My IDE makes |throw| look blue and bold, and it
looks familiar. It would stand out more (at least to me).
Garrett
>
> Mike
>
_______________________________________________
Es-discuss mailing list
[email protected]
https://mail.mozilla.org/listinfo/es-discuss
