I'm in need of "runtime decorators". That is, a class whose constructor is to take an instance of either the base class or a separate "runtime decorator" and add functionality to it. I don't know ahead of time what the type of the object will be. Here's an extremely contrived example of what I want to do (this strategy makes sense in the actual problem domain).

package Base;

sub new {
   my $package = shift;
   my $id = shift;

   return bless {
      id => $id,
   }, $package;
}

sub id {
   my ($self, $id) = @_;

   $self->{id} = $id if defined $id;
   return $self->{id};
}

1;

package NameDecorator;

sub new {
   my $package = shift;
   my $base_or_decorated = shift;
   
   my $self = $base_or_decorated->new(@_);
   $self->{name} = undef;

   return $self->{name};
}

sub name {
   my ($self, $name) = @_;

   $self->{name} = $name if defined $name;
   return $self->{name};
}

1;

...do the same for an AgeDecorator
[download]

Then I could use it like follows

use Base;
use NameDecorator;
use AgeDecorator;

my $decorated = AgeDecorator->new(NameDecorator->new(Base->new('id1'))
+);
$decorated->name('Edith');
$decorated->age(93);
[download]

I need the flexibility to be able to chain decorators together and still have available to methods added from the decorator before it. Is there a name for what I'm trying to do and can this be done easily without the help of a module or is there a module which can help me achieve this?

UPDATE: This is getting closer to what I want, but it still adds to the class rather than the object

package NameProto;

use strict;
use base qw(Base::Decorator);

sub new {
    my $self = shift->SUPER::new(@_);
    $self->{age} = 0;
    
    no strict 'refs';
    my $package = ref($self->{base});
    *{$package . '::name'} = sub {
        my ($self, $name) = @_;
        
        $self->{name} = $name if defined $name;
        return $self->{name};
    };
    
    return bless $self, $package;
}

sub name {
    return shift->{base}->name(@_);
}

1;
[download]

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