Or, if you need to do this during construction, consider subclassing HTML::TreeBuilder and selectively overriding methods.

That won't work if HTML::TreeBuilder has "hard coded" the name of HTML::Element, which I suspect it has.

As a hack, I'd just define methods in HTML::Element's space.

For long term, write the author of HTML::TreeBuilder and tell him to make the subclass an overrideable constant:

package HTML::TreeBuilder;
sub element_class { return "HTML::Element"; }
...
sub make_sub_node {
  ...
  my $ele = $self->element_class->new(...); #makes an HTML::Element pe
+rhaps
  ..
}
[download]

because then you can override that:

package My::TreeBuilder;
use base qw(HTML::TreeBuilder);
sub element_class { return "My::Element" };
package My::Element;
use base qw(HTML::Element);
sub my_additional_method { ... }
[download]

.

-- Randal L. Schwartz, Perl hacker