Re: uncaught exception in callback

Yoann Padioleau <[email protected]> writes:

> Hi,
>
> Is it possible to desactivate the capture of exceptions in 
> lablgtk code ? I want to debug my code and see where one
> my exception is launched but I can not get the backtrace
> because of lablgtk which does not let the exception 
> unwind to the top.

I saw this in gtkSignal.ml

   let user_handler = ref raise
   
   ...
   let connect  ~(sgn : ('a, _) t) ~callback ?(after=false) (obj : 'a obj) =
     let callback argv =
       let old = push_callback () in
       begin
         try sgn.marshaller callback argv
         with exn -> try !user_handler exn
         with exn ->
           Printf.eprintf "In callback for signal %s, uncaught exception: %s\n"
             sgn.name (Printexc.to_string exn);
           flush stderr
       end;
       if pop_callback old then emit_stop_by_name obj ~name:sgn.name
     in
     connect_by_name obj ~name:sgn.name ~callback:(Closure.create callback) ~after

Would it be possible to have instead a global flag that the user/programmer
can set to control this behaviour ? Or maybe just change a little
the code to something like this instead: 

let user_handler = ref (fun exn -> 
    Printf.eprintf "In callback for signal %s, uncaught exception: %s\n"
             sgn.name (Printexc.to_string exn);
           flush stderr;
    raise exn
 )


let connect  ~(sgn : ('a, _) t) ~callback ?(after=false) (obj : 'a obj) =
     let callback argv =
       let old = push_callback () in
       begin
         try sgn.marshaller callback argv
         with exn -> !user_handler exn
       end;
       if pop_callback old then emit_stop_by_name obj ~name:sgn.name
     in
     connect_by_name obj ~name:sgn.name ~callback:(Closure.create callback) ~after