use Scalar::Util qw(blessed dualvar isweak readonly refaddr reftype tainted
                        weaken isvstring looks_like_number set_prototype);

##</code><code>##

    $addr = refaddr "string";           # undef
    $addr = refaddr \$var;              # eg 12345678
    $addr = refaddr [];                 # eg 23456784

    $obj  = bless {}, "Foo";
    $addr = refaddr $obj;               # eg 88123488