[gambit-list] safe dynamic-wind

Marc Feeley feeley at iro.umontreal.ca
Sun Jan 8 02:30:02 EST 2006


Christian, in general I agree with your analysis.  This is a bug in  
with-exception-catcher and the REPL.  I have now changed it so that  
the dynamic-wind stack is properly wound and unwound.  This has  
required the addition of the procedures ##continuation-[graft|return]- 
with-winding.

I also uncovered a bug which caused the dynamic-environment (shown  
with the ,e command) to be wrong in higher frames, and a bug in  
dynamic-wind when re-entering the dynamic-wind.

However:

On 7-Jan-06, at 10:24 AM, Christian wrote:

> So it helps as long as I don't short-cut away my continuation in  
> the repl. It's also rather ugly that I don't immediately see the  
> position of the code where the error happened when being thrown  
> into the debugger.

I don't understand.  What is ugly?  You know about the ,y REPL  
command.  Do you mean you would like the system to implicitly execute  
this command when a new REPL is started?  I'm not convinced this is  
useful because the error message contains all this information, but  
in a different (more novice friendly) format.

> (For inspecting the lexical environment of the place where the  
> debugger happens I'll also step one up, and then it's too easy to  
> forget to step back before continuing.)
>
> At least for the repl, efficiency is no concern - could it be  
> changed to use safe continuations?

Changed.

Marc




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