yet another $A++

[stefp]

The French contest $A++ obfuscation contest is still raging! Do you know how to read a regexp? May be you thought you did.

use 5.6;
$a='';obfuscation=~m/(.{2,}?)(?{$a.=$1;})$/;
${eval+sprintf"v%1.1f",scalar+split'',$a}++