in reply to How to tell if I have a string, or a ref to a hash
perldoc -f ref
Returns a non-empty string if EXPR is a reference,
the empty string otherwise. If EXPR is not
specified, $_ will be used. The value returned
depends on the type of thing the reference is a
reference to. Builtin types include:
If the referenced object has been blessed into a
package, then that package name is returned instead.
You can think of “ref” as a “typeof” operator.