use Data::Dumper;
my $re_bad  = qr'@@([A-Z$#@_#]*) (?! [A-Za-z0-9$#@_] )'x;
print Dumper $re_bad;

##</code><code>##

$VAR1 = qr/(?x-ism:@@([A-Z$#@_#]*) (?! [A-Za-z0-9$#@_] )$
)/;

##</code><code>##

$VAR1 = qr/(?x-ism:@@([A-Z$#@_#]*) (?! [A-Za-z0-9$#@_] ))/;