Line/column numbers in user supplied exception handlers

[Dale P. Smith]

I'm trying to catch exceptions with my own handler and generate error
messages that include file/line number information.  If you call the
attached C program with an argument of 0, 1 or 2, you get these
different outputs:

address@hidden:~/$ ./foo 0
foo.scm:3:2: In expression (blorfl):
foo.scm:3:2: Unbound variable: blorfl

address@hidden:~/$ ./foo 1
ERROR: Unbound variable: blorfl
eval file returns: #f

address@hidden:~/$ ./foo 2
[some prefix here] foo.scm: ERROR: Unbound variable: blorfl
eval file returns: #f

I'd like to generate a message like:
[some prefix here] [error] foo.scm:3:2: Unbound variable: blorfl

How do I do it?  What's the best way to do this using the scm_
interface?

Thanks!
   -Dale

-- 
Dale P. Smith
Treasurer, Cleveland Linux Users Group http://cleveland.lug.net
Senior Systems Consultant, Altus Technologies Corporation
address@hidden
440-746-9000 x309

#include <guile/gh.h>

SCM 
my_handler(void *data, SCM tag, SCM throw_args)
{
    SCM ret;
    SCM eport = scm_current_error_port();
    
    scm_puts("[some prefix here] ", eport);
    
    scm_puts(data, eport);      /* filename */
    scm_puts(": ", eport);
    
    ret = scm_handle_by_message_noexit(data, tag, throw_args);
    scm_force_output(eport);
    
    return ret;
}


int
main(int argc, char *argv[])
{
    int val = atoi(argv[1]);
    SCM ret = SCM_EOL;
    SCM port = SCM_EOL;

    scm_init_guile();

    SCM_DEVAL_P = 1;
    SCM_RECORD_POSITIONS_P = 1;
    SCM_RESET_DEBUG_MODE;

    switch (val) {
    case 0:
        ret = gh_eval_file("foo.scm");
        break;
    case 1:
        ret = gh_eval_file_with_catch("foo.scm",
                                      scm_handle_by_message_noexit);
        break;
    case 2:
        ret = gh_eval_file_with_catch("foo.scm", my_handler);
        break;
    }
    
    port = scm_current_error_port();
    scm_puts("eval file returns: ", port);
    scm_prin1(ret, port, 0);
    scm_newline(port);

    return 0;
}

foo.scm
Description: Lotus Screencam