#!/usr/bin/perl
use strict;
use warnings;

my @num_to_name;
BEGIN {
    @num_to_name = qw(FOO BAR);
    eval "use constant $num_to_name[$_] => $_" for 0 .. $#num_to_name;
}

print "FOO-->", FOO(), "-->", $num_to_name[FOO];