Class::Unique - Create a unique subclass for every instance


Version 0.04


  package MyClass;

  use base 'Class::Unique';

  sub foo { print "foo!\n"; }
  sub bar { print "bar!\n"; }


  use MyClass;
  my $obj1 = MyClass->new;
  my $obj2 = MyClass->new;

  my $new_foo = sub { print "new foo!\n"; };
  $obj2->install( foo => $new_foo );

  $obj1->foo; $obj1->bar;
  $obj2->foo; $obj2->bar;


Class::Unique is a base class which provides a constructor and some utility routines for creating objects which instantiate into a unique subclass.

If MyClass is a subclass of Class::Unique, and inherrits Class::Unique's constructor, then every object returned by MyClass->new will be blessed into a dynamically created subclass of MyClass. This allows you to modify package data on a per-instance basis.

Class::Prototyped provides similar functionality; use this module if you want per-instance subclasses but you don't need a full prototype-based OO framework.


The following methods are inherrited.


Constructor. Returns a hash ref blessed into a new dynamically created package. If you need to override the constructor, make sure you get your object by using SUPER::new instead of blessing it yourself.

  package MyClass;
  use base 'Class::Unique';

  sub new { 
      my $class = shift;
      my $self = $class->SUPER::new( @_ );

      # fiddle with $self here....

      return $self;

Install a new symbol into an object's namespace. This can be used to dynamically override an inherrited subroutine, e.g.:

  my $code_ref = sub { print "wahoo!\n" };
  $obj->install( exclaim => $code_ref );

This is really just a shortcut for doing:

  my $pkg = ref $obj;
  no strict 'refs';
  *{ $pkg . '::subname' } = $code_ref;

You can also use install to add other package symbols:

  my @data = ( 1, 2, 3, 4 );
  $obj->install( data => \@data );


Mike Friedman, <friedo at friedo dot com>


Thanks to Stevan Little for submitting some unit tests.


Please report any bugs or feature requests to, or through the web interface at I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.


Copyright 2005 Mike Friedman, all rights reserved.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.