On Thu, 19 Dec 1996, Donald H. Mitchell wrote:

> Bruce Tobin wrote:
> > 
> > Is there a way to install a customized global error handler in Allegro/Win?
> > Something portable would be nice, but anything that works would be
> > appreciated.
> 
> I may not fully appreciate your question, but the condition system works
> under ACL 3.0 and following systems.  If you don't understand the
> condition system, I may be able to help you.

 I have a very basic understanding of the condition system, e.g. how to 
use (ignore-errors) and (handler-case).  These constructions seem not to 
have been designed with event-driven GUI applications in mind, and I 
can't find anything in CLTL2 that does seem to be so designed.

>  If you don't understand
> how to establish your own top-level loop w/ condition handling, I can
> give you example code. 

 Thanks.  Here's the kind of thing I want to be able to handle.  Suppose 
I design a dialog with one button, whose set-value-fn is 

(defun button-1-set-value-fn (x y z)
  (error "Oops! Wrong button!"))

Now I want to be able to run this dialog, trapping this and any other 
errors that may be generated by functions called from the dialog's event 
loop. I tried

  (ignore-errors (dialog-1))

 but this of course did not trap the error.  Obviously I don't want to 
have to put error-trapping code at the beginning of every event-handling 
function, but what is my alternative?