ref
- 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:
- SCALAR
- ARRAY
- HASH
- CODE
- REF
- GLOB
- LVALUE
- FORMAT
- IO
- VSTRING
- Regexp
You can think of
ref
as atypeof
operator.The return value
LVALUE
indicates a reference to an lvalue that is not a variable. You get this from taking the reference of function calls likepos()
orsubstr()
.VSTRING
is returned if the reference points to a version string.The result
Regexp
indicates that the argument is a regular expression resulting fromqr//
.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
Regexp
orIO
, or evenHASH
. Also,ref
doesn't take into account subclasses, likeisa
does.Instead, use
blessed
(in the Scalar::Util module) for boolean checks,isa
for specific class checks andreftype
(also from Scalar::Util) for type checks. (See perlobj for details and ablessed/isa
example.)See also perlref.