Re: Re: Extending object you don't create

[merlyn]

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
  ..
}

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 { ... }

.

-- Randal L. Schwartz, Perl hacker

[dws]

This is easier to pull off than that I thought. HTML::TreeBuilder already makes allowance for building a tree with objects other than instance of HTML::Element.

my $tree = new HTML::TreeBuilder(...);
# now replace 'HTML::Element' with my subclass
$tree->{'_element_class'} = 'HTML::MyElementSubclass';

Or, if this offends your sensibilities, subclass HTML::TreeBuilder, override new(), and invoke INHERITED::new() before resetting the element class.

This works with HTML::TreeBuilder 3.09.

[dcorbin]

Thanks. I didn't realize it had this ability. I will prostrate myself before the altar for a full day :)