Re: Lisp help: debug-on-error not effective twice?

[Lars Brinkhoff]

Lars Brinkhoff <lars@nocrew.org> writes:
> If I run this (in *scratch*) in GNU Emacs 21.3:
> 
>     (defun my-debug (&rest args)
>       (print "foo")
>       (throw 'error nil))
> 
>     (let ((debug-on-error t)
>           (debugger 'my-debug))
>       (catch 'error
>         (car))
>       (catch 'error
>         (car)))
> 
> I get one "foo" from my-debug and then the error "Wrong number of
> arguments: #<subr car>, 0".  Why isn't my-debug called twice?

It turns out that the debugger won't be calles unless there was an
input event in between two errors.  To work around this, I could
insert

        (incf num-nonmacro-input-events)

somewhere before the second error is signaled.  Would that have any
undesirable side effects?

-- 
Lars Brinkhoff,         Services for Unix, Linux, GCC, HTTP
Brinkhoff Consulting    http://www.brinkhoff.se/