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

my $aref = [ 'a' .. 'c' ];

warn 'ORIGINAL: $aref = ', join( q(, ), @{ $aref } );

for my $letter ( eval{ @{ $aref } } ) {
    $letter = 'z' . $letter;
}

warn 'NOT CHANGED: $aref = ', join( q(, ), @{ $aref } );

for my $letter ( @{ $aref } ) {
    $letter = 'z' . $letter;
}

warn 'CHANGED: $aref = ', join( q(, ), @{ $aref } );