Win8 Strawberry 5.8.9.5 (32)  Sun 11/22/2020  1:19:09
C:\@Work\Perl\monks
>perl
use strict;
use warnings;

use constant INVALID_DATA => ( q{invalid}, 0 );
use constant ADD_DATA => ( q{add}, 1 );
use constant REMOVE_DATA => ( q{remove}, 2 );
use constant MODES => ( \&ADD_DATA, \&REMOVE_DATA );

warn((ADD_DATA)[0]);
warn((ADD_DATA)[1]);

warn((MODES)[0]);
warn((MODES)[1]);

warn((MODES)[0]->());
warn((MODES)[1]->());
^Z
add at - line 11.
1 at - line 12.
CODE(0x1d2be34) at - line 14.
CODE(0x1cf904c) at - line 15.
add1 at - line 17.
remove2 at - line 18.