"But it seems daft to [force] you to copy the data to another instance"

package Factory;

sub create {
   my $class = shift;
   my $obj = 'Base::' . shift;
   return $obj->new();
}

package Base;

sub new {
   my $class = shift;
   my $self = { thing => 'foo' };
   return bless $self,$class;
}

package Base::Bold;
use base 'Base';

sub output {
   my $self = shift;
   return '<b>' . $self->{thing} . '</b>';
}

package Base::Italic;
use base 'Base';

sub output {
   my $self = shift;
   return '<i>' . $self->{thing} . '</i>';
}

package main;

my @things = (
   Factory->create('Bold'),
   Factory->create('Italic'),
);

print $_->output,$/ for @things;
[download]

And an HTML resume is different than a PDF resume: HTML and PDF are adjectives to the noun resume - an adjective qualifies, distinquishes, and specifies - hence, an HTML resume is one kind of resume (Resume::HTML), and a PDF resume is another kind (Resume::PDF). I you don't like this, then how about naming them Resume::AsHTML and Resume::AsPDF instead? ;)

jeffa

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)

Purists will argue that here are good reasons to subclass and there are lame reasons. I think this question falls into the grey area where I believe that it's "six of one, half-dozen of the other."

From the standpoint of extensibility and maintenance, there's little difference in my mind between supplying a new method in one class, or creating a new subclass. The effect of polymorphism makes it simple to select the method name if you use subclasses. But I don't think there is compelling as a reason for the approach.

I did find it instructive to consider the implications on memory use (and processing time) required to convert an XML resume' into an HTML resume' when each is implemented as a different type of object. If you simply supply different output methods, there's only one object ever put into memory. If you have different object types, then the conversion does require a copy operation. (I don't know if it's a big deal at this scale, but it is a consideration.)

I don't think it matters in this case overall, which approach you take. *BUT* I don't think it's "daft" (or daft enough) to go with the subclass approach. And if one of your objectives is to study and learn more about object design, then it's a good thing to do.

---v

Ooops. Didn't notice usernames were case-sensitive, so failed to log in before posting the above. Apologies.

Smylers