Yes, there is a bug. Using throw in asyncronous programming is a bug indeed.
You're right, "throw" function is in the same context in a sense that it
can access outer variables (it's called closure). But it is out of the
execution context in a sense that it doesn't happen in try-catch block.
That's how node.js executes it:
1st phase (starting). 49-50-51(try)-53-54(catch)-55
2nd phase (when data is received). 52
To confirm that you can get a stack trace from function(data) and see where
it is executed from. It won't be your function(req,res).
On Saturday, June 1, 2013 2:09:54 PM UTC+4, revin wrote:
>
> Hi,there:
>
> There may be a bug in try{...} frame that
> can't catch exceptions triggered by event listeners inside it.
>
> I'm so interested in nodeJs,
> but since it was young,
> it has a lot of drawbacks.
>
> I've noticed that nodeJs don't have a concurrent api interface,
> so I've decided to write my own framework extension based on nodeJs.
> But soon I've encountered a problem:
> 49:function(req,res){
> 50:try{
> 51: req.on("data",function(data){
> 52: throw new Error("FIXME: DebugTrap");
> 53: }
> 54:}cat1ch(e){}
> 55:}
> I think everyone, of course including me,
> will hope this works,
> but it won't.
>
> The weired thing is,
> when execution reaches line 52,
> it kinds of "inherited" the execution context from line 49,
> see it can access the variables, req and res.
> But the try{...} frame on line 50 can't catch Error on line 52.
>
> It's a V8 problem? Could it be fixed with nodeJs?
> I just don't want to build try{...} frames inside every event listener...
>
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