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.\" ========================================================================
.\"
.IX Title "UNIVERSAL::ref 3pm"
.TH UNIVERSAL::ref 3pm "2020-11-09" "perl v5.32.0" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
UNIVERSAL::ref \- Turns ref() into a multimethod
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 3
\&  # 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 \e $proxy, $class;
\&  }
\&  sub ref {
\&      my $self = shift @_;
\&      return $$self;
\&  }
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
This module changes the behavior of the builtin function \fBref()\fR. If
\&\fBref()\fR is called on an object that has requested an overloaded ref, the
object's \f(CW\*(C`\->ref\*(C'\fR method will be called and its return value used
instead.
.SH "USING"
.IX Header "USING"
To enable this feature for a class, \f(CW\*(C`use UNIVERSAL::ref\*(C'\fR in your
class. Here is a sample proxy module.
.PP
.Vb 5
\&  package Pirate;
\&  # Pirate pretends to be a Privateer
\&  use UNIVERSAL::ref;
\&  sub new { bless {}, shift }
\&  sub ref { return \*(AqPrivateer\*(Aq }
.Ve
.PP
Anywhere you call \f(CW\*(C`ref($obj)\*(C'\fR on a \f(CW\*(C`Pirate\*(C'\fR object, it will allow
\&\f(CW\*(C`Pirate\*(C'\fR to lie and pretend to be something else.
.SH "METHODS"
.IX Header "METHODS"
.IP "import" 4
.IX Item "import"
A pragma for \fBref()\fR\-enabling your class. This adds the calling class
name to a global list of \fBref()\fR\-enabled classes.
.Sp
.Vb 3
\&    package YourClass;
\&    use UNIVERSAL::ref;
\&    sub ref { ... }
.Ve
.IP "unimport" 4
.IX Item "unimport"
A pragma for \fBref()\fR\-disabling your class. This removes the calling
class name from a global list of \fBref()\fR\-enabled classes.
.SH "TODO"
.IX Header "TODO"
Currently UNIVERSAL::ref must be installed before any \fBref()\fR calls that
are to be affected.
.PP
I think \fBref()\fR always occurs in an implicit scalar context. There is no
accomodation for list context.
.PP
UNIVERSAL::ref probably shouldn't allow a module to lie to itself. Or
should it?
.SH "ACKNOWLEDGEMENTS"
.IX Header "ACKNOWLEDGEMENTS"
ambrus for the excellent idea to overload \fBdefined()\fR to allow Perl 5 to
have Perl 6's \*(L"interesting values of undef.\*(R"
.PP
chromatic for pointing out how utterly broken \fBref()\fR is. This fix
covers its biggest hole.
.SH "AUTHOR"
.IX Header "AUTHOR"
Joshua ben Jore \- jjore@cpan.org
.SH "LICENSE"
.IX Header "LICENSE"
The standard Artistic / \s-1GPL\s0 license most other perl code is typically
using.