I was trying to use perl's
__DATA__ subsection and was receiving the following warnings/errors:
readline() on unopened filehandle DATA main::DATA used only once
Well, after fighting with it for like 20 minutes, I did a Google search. After wandering around different mailing list archives, etc, I finally found a hint of a solution.
Apparently, using "Switch" (via "
use Switch;") does some kind of behind-the-scenes magic that breaks
__DATA__ section stuff.
I didn't find anything in
perldoc Switch that indicated it was a known bug. However, it is v5.8.5 so fairly old (2004, from RHEL 4.5) and the
Switch documentation says it is from 2003.