package MyConstants;

use strict;
our $AUTOLOAD;

sub import {
    my $package = shift;
    if ($_[0] eq 'AUTOLOAD') {
        my $caller = caller;
        no strict 'refs';
        *{$caller.'::AUTOLOAD'} = \&{$package.'::AUTOLOAD'};
    }
}

# Constants
use constant {
    NIL => 0,
    FOO => 1,
    BAR => 2,
};

sub AUTOLOAD {
    (my $func = $AUTOLOAD) =~ s/.*:://;
    no strict 'refs';
    *{$AUTOLOAD} = \&{__PACKAGE__.$func};
    goto &$func;
}
1;