??? ref EXPR
??? ref???? Returns a non-empty string if EXPR is a reference, the empty
??????????? string otherwise. If EXPR is not specified, $_ will be used. The
??????????? value returned depends on the type of thing the reference is a
??????????? reference to. Builtin types include:
??????????????? SCALAR
??????????????? ARRAY
??????????????? HASH
??????????????? CODE
??????????????? REF
??????????????? GLOB
??????????????? LVALUE
??????????? If the referenced object has been blessed into a package, then
??????????? that package name is returned instead. You can think of "ref" as
??????????? a "typeof" operator.
??????????????? if (ref($r) eq "HASH") {
??????????????????? print "r is a reference to a hash.\n";
??????????????? }
??????????????? unless (ref($r)) {
??????????????????? print "r is not a reference at all.\n";
??????????????? }
??????????????? if (UNIVERSAL::isa($r, "HASH")) {? # for subclassing
??????????????????? print "r is a reference to something that isa hash.\n";
??????????????? }
??????????? See also perlref.
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