But the one jcwren posted can be easily abused:

$==1,$^^=2,$^^^=$=^=$^^^=$=;
$==1,$^^=2,$=^=$^^^=$=^=$^^;
[download]

The traditional method (the swap you show) is only easily obfuscated by something like

# if you're allowed to over-write $( and $)
($),$() = ($(,$));
[download]

Kudos to the person who explains my XOR obfuscation.

japhy -- Perl and Regex Hacker