taken from console.js in core:
exports.trace = function(label) {
// TODO probably can to do this better with V8's debug object once that is
// exposed.
var err = new Error;
err.name = 'Trace';
err.message = label || '';
Error.captureStackTrace(err, arguments.callee);
console.error(err.stack);
};
Am Freitag, 14. Dezember 2012 08:06:24 UTC+1 schrieb Jonathan Dickinson:
>
> It looks like you can only do it with errors:
>
> (new Error()).stack
>
> Taking require() as an example (if you were in control of it) you would
> make require() add the stack trace to the module before any code in the
> module executes. Now within the context of the B load you find out that it
> is a cycle back to A, so your require() method would do something like:
>
> function require(arg) {
> var stackInfo = getStackInfo(arg);
> if (stackInfo) {
> // We can do this because the 'prologue' of "A" would have populated
> the stack trace in our internal modules set.
> throw new CycleError(getStackInfo(arg) + " [" + arg + "] has a cyclic
> dependency with [" + currentModule + "] " + (new Error()).stack;
> }
> }
>
> Alternatively you could require that your components advertise their
> dependencies up-front (similar to package.json). You could then discover
> cycles (and load order, by the way) before running anything using Tarjan's
> Strong Connected Components Algorithm:
> http://en.wikipedia.org/wiki/Tarjan's_strongly_connected_components_algorithm
> .
>
> At the end of the day though getting source information for a function
> could be an amazing addition for so many development cases, especially
> providing useful debugging info.
>
> On Friday, 14 December 2012 06:23:16 UTC+2, Martin Heidegger wrote:
>>
>> Hello everybody,
>>
>> I am writing on a system that should detect and resolve dependencies of
>> code before executing it. So method A references method B so method B needs
>> to be called before A. So far that works fine, however when I throw a
>> circular dependency error message all the error message says is "[function]
>> has a circular dependency to [function]"... thats very few information for
>> debugging. I want to improve on that by at least displaying the line-number
>> of the methods. So far I haven't found a way to do that. It should be
>> possible because the VM should know where a method has been written (else
>> it could not tell me the location on a stacktrace).
>>
>> Have I missed something? Is this worth a feature request?
>>
>> yours
>> Martin.
>>
>
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