# this is A.pm
package A;

BEGIN { print "Haven't used B yet\n" }
use B;
BEGIN { print "Just used B\n" }


END { print "Exiting A\n" }

1;



# this is B.pm
package B ;

BEGIN {
  # open a file or exit(1) with a message to STDERR
  open B_FH, 'somefile' or exit warn "somefile: $!\n" ;
}

END {
  close B_FH ;
  print "Exiting B\n" ;
}

1;