$ perl -MO=Deparse,-p,-q -E 'print $ads{$this_ad} "$line\n";'
String found where operator expected at -e line 1, near "} "$line\n""
        (Missing operator before  "$line\n"?)
syntax error at -e line 1, near "} "$line\n""
-e had compilation errors.

$ perl -MO=Deparse,-p,-q -E 'print { $ads{$this_ad} } "$line\n";'
use feature 'current_sub', 'bitwise', 'evalbytes', 'fc', 'postderef_qq', 'say', 'state', 'switch', 'unicode_strings', 'unicode_eval';
print({$ads{$this_ad};} ($line . "\n"));
-e syntax OK