use strict;
my $code;
{
	#slurp mode (http://perldoc.perl.org/perlvar.html)
	local $/;
	$code = <DATA>;
}
my $re = qr {\@([a-z][a-z0-9_]*)\[\d+]};
$code =~ s{$re}{
	"\@$1\[" . int(rand(99999)) . "]"
	}eg;
print $code; #show output example

__DATA__
@a = ("'hello world'",'print ', ';');
eval(@a[1] . @a[0] . @a[2]);