package MyConstants;
require Exporter;
@ISA = qw(Exporter);
our @EXPORT = do {
                    no strict 'refs';
                    keys %{ __PACKAGE__ . '::'};
                 };

use constant VAR1 => VAL1;
use constant VAR2 => VAL2;
#--- 500 more of these
1;

##</code><code>##

use MyConstants;