the base class we'll decorate

package Print;

# Print class to print a string 

use warnings;
use strict;
use Carp;

sub new {
        my $type = shift;
        my $class = ref $type || $type;
        # TEXT is private!
        my $self = {
                TEXT => undef,
        };
        my $closure = sub {
                my $field = shift;
                if (@_) { $self->{$field} = shift; }
                return $self->{$field};
        };
        bless ($closure,$class);
        return $closure;
}

# a public accessor to set and get TEXT
sub text { &{ $_[0] }("TEXT", @_[1 .. $#_]) }

# a public method to print TEXT

sub print { 
        my $self = shift;
        print $self->text . "\n";
}

1;

A HTML version

package PrintHtml;

# Print class to print a string in html format 

use warnings;
use strict;
use Carp;
use Print;

sub new {
        my $type = shift;
        my $class = ref $type || $type;
        # itsPrint is private!
        my $itsPrint = shift;
        my $self = {
                itsPrint => $itsPrint,
        };
        my $closure = sub {
                my $field = shift;
                return $self->{$field};
        };
        bless ($closure,$class);
        return $closure;
}

sub print {
        my $self = shift;
        print "<p>\n";
        &{ $_[0]}("itsPrint")->print;
        print "</p>\n";
}
1;

A Latex version

package PrintLatex;

# Print class to print a string in latex format 

use warnings;
use strict;
use Carp;
use Print;

sub new {
        my $type = shift;
        my $class = ref $type || $type;
        # itsPrint is private!
        my $itsPrint = shift;
        my $self = {
                itsPrint => $itsPrint,
        };
        my $closure = sub {
                my $field = shift;
                return $self->{$field};
        };
        bless ($closure,$class);
        return $closure;
}

sub print {
        my $self = shift;
        print "\\begin{paraf}\n";
        &{ $_[0]}("itsPrint")->print;
        print "\\end{paraf}\n";
}

1;

The caller...

#!/usr/bin/perl

use warnings;
use strict;
use Print;
use PrintHtml;
use PrintLatex;

print "Text...\n";
my $print = Print->new();
$print->text("hello");
$print->print;

print "\nHTML...\n";
my $html = PrintHtml->new($print);
$html->print;

print "\nLatex...\n";
my $latex = PrintLatex->new($print);
$latex->print;