... not in perl versions older than 5.10 ...

In any version of Perl, the command-line  perldoc perlop (and other docs) can be a very welcome local feature sanity check. It's saved me wasted motion more than once.

The on-line perlop (and on-line documentation in general) is tied to the most recent Perl version and is perhaps a bit overenthusiastic in presenting new features, but even this can be dialed back to previous versions (back to 5.8, IIRC).