UNIVERSAL::ref(3) Turns ref() into a multimethod


# True! Wrapper pretends to be Thing.
ref( Wrapper->new( Thing->new ) )
eq ref( Thing->new );
package Thing;
sub new { bless [], shift }
package Wrapper;
sub new {
my ($class,$proxy) = @_;
bless \ $proxy, $class;
sub ref {
my $self = shift @_;
return $$self;


This module changes the behavior of the builtin function ref(). If ref() is called on an object that has requested an overloaded ref, the object's "->ref" method will be called and its return value used instead.


To enable this feature for a class, "use UNIVERSAL::ref" in your class. Here is a sample proxy module.

  package Pirate;
  # Pirate pretends to be a Privateer
  use UNIVERSAL::ref;
  sub new { bless {}, shift }
  sub ref { return 'Privateer' }

Anywhere you call "ref($obj)" on a "Pirate" object, it will allow "Pirate" to lie and pretend to be something else.


A pragma for ref()-enabling your class. This adds the calling class name to a global list of ref()-enabled classes.

    package YourClass;
    use UNIVERSAL::ref;
    sub ref { ... }
A pragma for ref()-disabling your class. This removes the calling class name from a global list of ref()-enabled classes.


Currently UNIVERSAL::ref must be installed before any ref() calls that are to be affected.

I think ref() always occurs in an implicit scalar context. There is no accomodation for list context.

UNIVERSAL::ref probably shouldn't allow a module to lie to itself. Or should it?


ambrus for the excellent idea to overload defined() to allow Perl 5 to have Perl 6's ``interesting values of undef.''

chromatic for pointing out how utterly broken ref() is. This fix covers its biggest hole.


Joshua ben Jore - [email protected]


The standard Artistic / GPL license most other perl code is typically using.