Perl 5 version 24.4 documentation
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:
You can think of ref as a
The return value
LVALUEindicates a reference to an lvalue that is not a variable. You get this from taking the reference of function calls like pos or substr.
VSTRINGis returned if the reference points to a version string.
Regexpindicates that the argument is a regular expression resulting from qr//.
If the referenced object has been blessed into a package, then that package name is returned instead. But don't use that, as it's now considered "bad practice". For one reason, an object could be using a class called
IO, or even
HASH. Also, ref doesn't take into account subclasses, like isa does.
Instead, use blessed (in the Scalar::Util module) for boolean checks, isa for specific class checks and reftype (also from Scalar::Util) for type checks. (See perlobj for details and a blessed /isa example.)
See also perlref.