I've refactored Template::Declare::Tags and introduced the long over-due TagSet feature to TD.

HTML tag list and other related info have been moved to HTML::TagSet, and XUL::TagSet is also added. We can now control which tag set to use by the following lines of code:

package MyApp::Templates;
use Template::Declare::Tags qw/ XUL::TagSet /;
use base 'Template::Declare';

     template foo => sub {
         window { attr { ... } groupbox { .... } }
     };

And it's also possible to specify multiple tag sets:

use Template::Declare::Tags qw/ XUL::TagSet HTML::TagSet /;

(This example is not very realistic BTW.)

By default, Template::Declare::Tags uses HTML::TagSet so that existing code won't break.

The user can define their own tag set classes as long as these classes subclass Template::Declare::TagSet and implement the corresponding methods (i.e. get_tag_list, get_alternate_spelling, and can_combine_empty_tags).

See the POD in these classes for more info :)

Now I'm considering adding the XML namespace support to TD. I'm proposing the following design:

     package html;
     use Template::Declare::Tags 'HTML::Tags' => { tag_prefix => 'html:' };

     package MyXulApp::Templates;
     use Template::Declare::Tags 'XUL::Tags';
     template foo => sub {
         groupbox {
             html::p { 'hello, XML!' }
             html::table {}
         }
     };

And show('foo') will give:

  <groupbox>
    <html:p>hello, XML!</html:p>
    <html:table></html:table>
  </groupbox>

Thoughts? Comments?