use strict;
use warnings;

use String::FixedLen;

tie my $str, 'String::FixedLen', 4;

sub p { print "[$str]\n" }

$str = 'a';              p;
$str .= 'bcde';          p;
$str = "hello, world\n"; p;
$str = "wis$str";        p;
$str = 9999 + 2;         p;
$str = sqrt(2);          p;