use strict;
use warnings;

sub Invoker::first_callback {
   my $z = shift;
   print "in first_callback, z=$z\n";
   return 1;
}

sub Invoker::last_callback {
   my $z = shift;
   print "in last_callback, z=$z\n";
   return 2;
}

sub invoker
{
   my ($name, $z) = @_;
   my $handler = 'Invoker::' . $name . "_callback";
   no strict 'refs';
   my $rc = eval { &$handler($z) };
   return defined($rc) ? $rc : -1;
}

# Main program for testing ---------------------------------

for my $name ( "first", "last", "fred" ) {
   my $rc = invoker( $name, $name . '-arg' );
   print "$name: rc=$rc\n";
}