[plt-scheme] Re: Exception trace

D'oh!

Wouldn't you know it: a second after I sent that email I figured out  
what was going wrong. The question about stack traces still stands  
out of academic interest, however.

Cheers,

-- Dave

> Apologies if this is obvious... I scanned the docs but couldn't  
> find an answer.
>
> I'm getting an exn:fail somewhere deep in my code that I want to  
> prevent. However, the trace I get back is very long and MzScheme  
> gives up and writes an ellipsis before I get to the useful bit of  
> the trace:
>
> === context ===
> /data/www/uk/ac/qmul/sbcs/www2/demo/lib/lylux/view/filter.ss:68:4
> /data/www/uk/ac/qmul/sbcs/www2/demo/lib/lylux/view/xshtml-render.ss: 
> 279:14: loop
> /data/www/uk/ac/qmul/sbcs/www2/demo/lib/lylux/view/xshtml-render.ss: 
> 233:12: display-element
> /data/www/uk/ac/qmul/sbcs/www2/demo/lib/lylux/view/xshtml-render.ss: 
> 329:14: loop
> /data/www/uk/ac/qmul/sbcs/www2/demo/lib/lylux/view/xshtml-render.ss: 
> 233:12: display-element
> /data/www/uk/ac/qmul/sbcs/www2/demo/lib/lylux/view/xshtml-render.ss: 
> 329:14: loop
> /data/www/uk/ac/qmul/sbcs/www2/demo/lib/lylux/view/xshtml-render.ss: 
> 233:12: display-element
> /data/www/uk/ac/qmul/sbcs/www2/demo/lib/lylux/view/xshtml-render.ss: 
> 329:14: loop
> /data/www/uk/ac/qmul/sbcs/www2/demo/lib/lylux/view/xshtml-render.ss: 
> 233:12: display-element
> /data/www/uk/ac/qmul/sbcs/www2/demo/lib/lylux/view/xshtml-render.ss: 
> 329:14: loop
> /data/www/uk/ac/qmul/sbcs/www2/demo/lib/lylux/view/xshtml-render.ss: 
> 233:12: display-element
> /data/www/uk/ac/qmul/sbcs/www2/demo/lib/lylux/view/xshtml-render.ss: 
> 329:14: loop
> /data/www/uk/ac/qmul/sbcs/www2/demo/lib/lylux/view/xshtml-render.ss: 
> 233:12: display-element
> /data/www/uk/ac/qmul/sbcs/www2/demo/lib/lylux/view/render.ss:31:4:  
> render-xshtml
> define/contract-contract-id-render-xshtml
> define/contract-contract-id-render-xshtml
> ...
>
> The error is happening in the middle of a bunch of redirects  
> between my web site and another (authentication) site, and it might  
> be caused by my code or someone else's. I really need to extend  
> this trace to find out which high level procedure is the root of  
> the problem.
>
> I've tried sticking:
>
>     (require (lib "errortrace.ss" "errortrace"))
>
> in the main file for my program, but it doesn't seem to make any  
> difference to the output. I have a hunch that this won't work  
> because I'm using web-server and Noel Welsh's "instaweb" package  
> (one of the Schematics packages on Planet), one of which does  
> something clever with compilation that I don't understand.
>
> Is there any way I can increase the length of the stack trace from  
> the MzScheme error handler so I can see where this error is coming  
> from?
>
> Cheers,
>
> -- Dave