#!/usr/bin/perl

use v5.14;
use warnings;
use Readonly ();

BEGIN {
    *ro_ref = \&Readonly::Scalar1;
}

my @arr = (2, 3, 4);
ro_ref my $arr, \@arr;

@arr = (3, 4, 5);
say "@$arr";
eval {$arr = [4, 5, 6]; 1} || warn $@;

__DATA__
Modification of a read-only value attempted at /home/jo/Programs/play-scripts/ro-ref.pl line 16.
3 4 5