Re: Package name

["Randy Brukardt" <randy@rrsoftware.com>]

Marin David Condic wrote in message <9du16o$fr3$1@nh.pace.co.uk>...
>It would be useful for diagnostics in the event of various errors or
other
>conditions. Maybe even have "Current_Context'Line_Number" and similar
>capabilities? One would wish that Exception_Message and
>Exception_Information had this sort of information in their returned
strings
>(Never seen it myself in the implementations I've used)...

You've obviously never used Janus/Ada. It includes a complete traceback
of the calls in Exception_Information:

   ** Unhandled CONSTRAINT_ERROR
      Index or Subtype out of bounds - Pos of Error Value =  12
   On Line Number 7 In PROC.FOO.BAR
   Called from line number 123 In PROC.FOO
   Called from line number 11 In PROC

(It always has had this, but there wasn't a clean way to get it in Ada
83 except to let the program terminate with an unhandled exception.)
This is a godsend when debugging. (It also keeps limited information
about reraised exceptions, so the original traceback isn't lost.)

All of the Claw exception handlers display Exception_Information in
order to be able to access this information. On some compilers,
Exception_Information is pretty useless (and we try to debug Claw with
other compilers, usually Janus/Ada and GNAT) unless the problem is
compiler-specific. One problem with Claw is that many exceptions are
raised by a subprogram Raise_Windows_Error (which sets up an appropriate
Exception_Message), so you need the line number and package of the call
to that routine in order to find out anything useful. Only Janus/Ada
gives enough information to easily debug such exceptions.

                Randy Brukardt.


            Randy.