Eeek, how embarrassing. This seems to have been fixed while I wasn't looking, and/or my testing wasn't as complete as I thought. I should have re-tested before emailing. My apologies for wasting everyone's time.
The debugger step-back-ability isn't there in Chrome, at least, but that's a much smaller problem. ________________________________ From: Rick Waldron [[email protected]] Sent: Friday, May 11, 2012 16:10 To: Brendan Eich Cc: Domenic Denicola; [email protected] Subject: Re: Re-throwing errors On Fri, May 11, 2012 at 2:43 PM, Brendan Eich <[email protected]<mailto:[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 _______________________________________________ es-discuss mailing list [email protected]<mailto:[email protected]> https://mail.mozilla.org/listinfo/es-discuss _______________________________________________ es-discuss mailing list [email protected]<mailto:[email protected]> https://mail.mozilla.org/listinfo/es-discuss
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