On Fri, May 11, 2012 at 2:43 PM, Brendan Eich <[email protected]> wrote:
> Domenic Denicola wrote:
>
>> Consider:
>>
>> try {
>> doStuff();
>> } catch (e) {
>> console.log("uh oh, got an e", e);
>> throw e;
>> }
>>
>> In Node and in all browsers I've tested with, this currently loses the
>> stack trace for `e`, and more importantly loses debugger step-back-ability
>> in tools like Firebug and Web Inspector.
>>
>> One solution would be to hope V8 and the browser vendors simply don't
>> throw away this stack trace, like they do currently. This seems like a win
>> to me, but the fact that it hasn't happened implies there must be something
>> wrong with the idea, e.g. maybe it breaks down in less-than-trivial cases.
>> Is that true?
>>
>
This is fascinating, but I can't reproduce - can you confirm:
https://gist.github.com/2662158
Rick
> So V8 overwrites e.stack on the re-throw?
>
> SpiderMonkey does not:
>
> js> function f() {
>
> try {
> doStuff();
> } catch (e) {
> console.log("uh oh, got an e", e);
> throw e;
> }
> }
> js> function g() {f()}
> js> function h() {g()}
> js> function doStuff() {uh.oh}
> js> console = {log: print}
> ({log:function print() {[native code]}})
> js> try {h()}catch (e){E=e}
> uh oh, got an e ReferenceError: uh is not defined
> (new ReferenceError("uh is not defined", "typein", 11))
> js> e.stack
> typein:15: ReferenceError: e is not defined
> js> E.stack
> "doStuff@typein:11\nf@typein:**3\ng@typein:9\nh@typein:10\n@**typein:14\n"
>
> Since the explicit re-throw is not creating the exception object, it
> should not be mutating it to clobber the original .stack value.
>
> /be
>
> If so, then in C++ and C# they solve this by saying that an empty `throw`
>> is an explicit re-propagation [1]. Would this be a possible feature to
>> introduce into Harmony?
>>
>> [1]:
>> http://winterdom.com/2002/09/**rethrowingexceptionsinc<http://winterdom.com/2002/09/rethrowingexceptionsinc>
>> ______________________________**_________________
>> es-discuss mailing list
>> [email protected]
>> https://mail.mozilla.org/**listinfo/es-discuss<https://mail.mozilla.org/listinfo/es-discuss>
>>
> ______________________________**_________________
> es-discuss mailing list
> [email protected]
> https://mail.mozilla.org/**listinfo/es-discuss<https://mail.mozilla.org/listinfo/es-discuss>
>
_______________________________________________
es-discuss mailing list
[email protected]
https://mail.mozilla.org/listinfo/es-discuss
