<pre>
$order = "ABCDE";

    %valByKey    
{ A => \A_value }
{ B => \B_value }
{ C => \C_value }
{ D => \D_value }
{ E => \E_value }
</pre>
##</code><code>##

sub getByKey {
    my $key = shift;

    ## to top.
    $order =~ s[(^.*)($key)][$2$1]; 

    ## Needs quotemetaing and adjusting for 3-char keys
    ## may also require C<no warnings 'undefined'> 
    ## to prevent that when the item being moved is at
    ## the beginning or the end of the string.

    ## to bottom ## $order =~ s[($key)(.*$)][$2$1];
    ## up one    ## $order =~ s[(.?)($key)][$2$1];
    ## down one  ## $order =~ s[($key)(.?)][$2$1];
    ## up two    ## $order =~ s[(..)?($key)][$2$1];
    ## down two  ## $order =~ s[($Key)(..)?][$1$2];
	
    return $valByKey{ $key };;
}

##</code><code>##

$order = "CABDE";

    %valByKey    
{ A => \A_value }
{ B => \B_value }
{ C => \C_value }
{ D => \D_value }
{ E => \E_value }