Re: C-g does not interrupt lisp code (emacs 21)

[Philippe Waroquiers]

> compile it with -g and step through the loop under a debugger.  That
> way you will really see what is happening.

I agree with this. 
Note that when having to debug a huge program that you do not know very well 
(this is emacs for me), external tracing of system call can help a lot in 
some cases to reduce the scope of where to search.
In this particular case, the syscall tracing almost directly pointed to the 
problem 
(sigblock and no sigunblock). gdb was then used to refine this initial 
reduction.

The difficulty in this case is that it is "normal" that the program enters in
an infinite loop and it is an external interrupt (signal) that puts it out of
the loop.
The bug is in fact in a piece of code unrelated to the
code executed in the loop (as far as I have understood :).

> 
> In general, if you are a programmer and you hesitate to run a program
> under a debugger to diagnose the problem, the best single way you can
> develop your skills is to learn to love the debugger.
For sure, it is a good advice to master the debugger. However, due to
the quality of emacs, I have not much occasions to develop my skills :).

Thanks for the feedback and the nice work on emacs.


-- 
Philippe WAROQUIERS                  Eurocontrol - Central Flow Management Unit
philippe.waroquiers@eurocontrol.int  Rue de la fusee, 96
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